Misplaced Pages

#642357

70-530: The Blackjack Joe Formation consists of 600 meters (2,000 ft) of argillaceous ( clay -rich) sediments. Detrital zircon geochronology establishes a minimum age for the formation of 1474 ± 13 million years. The formation is intruded by the Ruin Granite , with a radiometric age of 1436 ± 2 million years, thus constraining the age of the Blackjack Formation to 1474 to 1436 million years. The formation

140-402: A monochromator . Alternatively, the entire wavelength range is measured using a Fourier transform instrument and then a transmittance or absorbance spectrum is extracted. This technique is commonly used for analyzing samples with covalent bonds . The number of bands roughly correlates with symmetry and molecular complexity. A variety of devices are used to hold the sample in the path of

210-401: A "two-beam" setup (see figure), can correct for these types of effects to give very accurate results. The Standard addition method can be used to statistically cancel these errors. Nevertheless, among different absorption-based techniques which are used for gaseous species detection, Cavity ring-down spectroscopy (CRDS) can be used as a calibration-free method. The fact that CRDS is based on

280-426: A bond between atoms is stretched, for instance, there comes a point at which the bond breaks and the molecule dissociates into atoms. Thus real molecules deviate from perfect harmonic motion and their molecular vibrational motion is anharmonic . An empirical expression that fits the energy curve of a diatomic molecule undergoing anharmonic extension and compression to a good approximation was derived by P.M. Morse , and

350-747: A convenient stand-off method to sort plastic of different polymers ( PET , HDPE , ...). Other developments include a miniature IR-spectrometer that's linked to a cloud based database and suitable for personal everyday use, and NIR-spectroscopic chips that can be embedded in smartphones and various gadgets. In catalysis research it is a very useful tool to characterize the catalyst, as well as to detect intermediates Infrared spectroscopy coupled with machine learning and artificial intelligence also has potential for rapid, accurate and non-invasive sensing of bacteria. The complex chemical composition of bacteria, including nucleic acids, proteins, carbohydrates and fatty acids, results in high-dimensional datasets where

420-452: A function of infrared wavelength (or equivalently, wavenumber ). As described above, the sample's spectrum is always compared to a reference. An alternate method for acquiring spectra is the "dispersive" or "scanning monochromator " method. In this approach, the sample is irradiated sequentially with various single wavelengths. The dispersive method is more common in UV-Vis spectroscopy , but

490-509: A graph of infrared light absorbance (or transmittance ) on the vertical axis vs. frequency , wavenumber or wavelength on the horizontal axis. Typical units of wavenumber used in IR spectra are reciprocal centimeters , with the symbol cm . Units of IR wavelength are commonly given in micrometers (formerly called "microns"), symbol μm, which are related to the wavenumber in a reciprocal way. A common laboratory instrument that uses this technique

560-479: A hexagonal array in two dimensions. The fourth oxygen ion is not shared with another tetrahedron and all of the tetrahedra "point" in the same direction; i.e. all of the unshared oxygen ions are on the same side of the sheet. These unshared oxygen ions are called apical oxygen ions. In clays, the tetrahedral sheets are always bonded to octahedral sheets formed from small cations, such as aluminum or magnesium, and coordinated by six oxygen atoms. The unshared vertex from

630-400: A net negative charge and may be bonded together either by individual cations (such as potassium in illite or sodium or calcium in smectites) or by positively charged octahedral sheets (as in chlorites ). Clay minerals include the following groups: Mixed layer clay variations exist for most of the above groups. Ordering is described as a random or regular order and is further described by

700-403: A number of other salts such as potassium bromide or calcium fluoride are also used). The plates are transparent to the infrared light and do not introduce any lines onto the spectra. With increasing technology in computer filtering and manipulation of the results, samples in solution can now be measured accurately (water produces a broad absorbance across the range of interest, and thus renders

770-794: A sample to be "IR active", it must be associated with changes in the molecular dipole moment. A permanent dipole is not necessary, as the rule requires only a change in dipole moment. A molecule can vibrate in many ways, and each way is called a vibrational mode . For molecules with N number of atoms, geometrically linear molecules have 3 N  – 5 degrees of vibrational modes, whereas nonlinear molecules have 3 N  – 6 degrees of vibrational modes (also called vibrational degrees of freedom). As examples linear carbon dioxide (CO 2 ) has 3 × 3 – 5 = 4, while non-linear water (H 2 O) , has only 3 × 3 – 6 = 3. Simple diatomic molecules have only one bond and only one vibrational band. If

SECTION 10

#1732891212643

840-507: A significant component. For example, argillaceous limestones are limestones consisting predominantly of calcium carbonate , but including 10-40% of clay minerals: such limestones, when soft, are often called marls . Similarly, argillaceous sandstones such as greywacke , are sandstones consisting primarily of quartz grains, with the interstitial spaces filled with clay minerals. Infrared spectroscopy Infrared spectroscopy ( IR spectroscopy or vibrational spectroscopy )

910-622: A technique for performing vibrational spectroscopy in a transmission electron microscope (TEM). In combination with the high spatial resolution of the TEM, unprecedented experiments have been performed, such as nano-scale temperature measurements, mapping of isotopically labeled molecules, mapping of phonon modes in position- and momentum-space, vibrational surface and bulk mode mapping on nanocubes, and investigations of polariton modes in van der Waals crystals. Analysis of vibrational modes that are IR-inactive but appear in inelastic neutron scattering

980-420: A traditional technique establishing fundamental occurrences or petrologic relationships. Clay minerals are common weathering products (including weathering of feldspar ) and low-temperature hydrothermal alteration products. Clay minerals are very common in soils, in fine-grained sedimentary rocks such as shale , mudstone , and siltstone and in fine-grained metamorphic slate and phyllite . Given

1050-540: A very common material, and is the oldest known ceramic . Prehistoric humans discovered the useful properties of clay and used it for making pottery . The chemistry of clay, including its capacity to retain nutrient cations such as potassium and ammonium , is important to soil fertility. Because the individual particles in clay are less than 4 micrometers (0.00016 in) in size, they cannot be characterized by ordinary optical or physical methods. The crystallographic structure of clay minerals became better understood in

1120-529: Is a Fourier transform infrared (FTIR) spectrometer . Two-dimensional IR is also possible as discussed below . The infrared portion of the electromagnetic spectrum is usually divided into three regions; the near- , mid- and far- infrared, named for their relation to the visible spectrum. The higher-energy near-IR, approximately 14,000–4,000 cm (0.7–2.5 μm wavelength) can excite overtone or combination modes of molecular vibrations . The mid-infrared, approximately 4,000–400 cm (2.5–25 μm)

1190-570: Is also possible at high spatial resolution using EELS. Although the spatial resolution of HREELs is very high, the bands are extremely broad compared to other techniques. By using computer simulations and normal mode analysis it is possible to calculate theoretical frequencies of molecules. IR spectroscopy is often used to identify structures because functional groups give rise to characteristic bands both in terms of intensity and position (frequency). The positions of these bands are summarized in correlation tables as shown below. A spectrograph

1260-463: Is also used in forensic analysis in both criminal and civil cases, for example in identifying polymer degradation . It can be used in determining the blood alcohol content of a suspected drunk driver. IR spectroscopy has been used in identification of pigments in paintings and other art objects such as illuminated manuscripts . Infrared spectroscopy is also useful in measuring the degree of polymerization in polymer manufacture. Changes in

1330-511: Is called the Morse function . Using the Schrödinger equation leads to the selection rule for the system undergoing vibrational changes : △ v = ± 1 , ± 2 , ± 3 , ⋅ ⋅ ⋅ {\displaystyle \bigtriangleup v=\pm 1,\pm 2,\pm 3,\cdot \cdot \cdot } In order for a vibrational mode in

1400-504: Is formed from a stack of layers interspaced with the interlayers. Clay minerals can be classified as 1:1 or 2:1. A 1:1 clay would consist of one tetrahedral sheet and one octahedral sheet, and examples would be kaolinite and serpentinite . A 2:1 clay consists of an octahedral sheet sandwiched between two tetrahedral sheets, and examples are talc , vermiculite , and montmorillonite . The layers in 1:1 clays are uncharged and are bonded by hydrogen bonds between layers, but 2:1 layers have

1470-504: Is generally used to study the fundamental vibrations and associated rotational–vibrational structure. The far-infrared, approximately 400–10 cm (25–1,000 μm) has low energy and may be used for rotational spectroscopy and low frequency vibrations. The region from 2–130 cm , bordering the microwave region, is considered the terahertz region and may probe intermolecular vibrations. The names and classifications of these subregions are conventions, and are only loosely based on

SECTION 20

#1732891212643

1540-456: Is guided through an interferometer and then through the sample (or vice versa). A moving mirror inside the apparatus alters the distribution of infrared light that passes through the interferometer. The signal directly recorded, called an "interferogram", represents light output as a function of mirror position. A data-processing technique called Fourier transform turns this raw data into the desired result (the sample's spectrum): light output as

1610-423: Is important for many clinical settings where faster susceptibility testing would decrease unnecessary blind-treatment with broad-spectrum antibiotics. The main limitation of this technique for clinical applications is the high sensitivity to technical equipment and sample preparation techniques, which makes it difficult to construct large-scale databases. Attempts in this direction have however been made by Bruker with

1680-465: Is in the food industry to measure the concentration of various compounds in different food products. Infrared spectroscopy is also used in gas leak detection devices such as the DP-IR and EyeCGAs. These devices detect hydrocarbon gas leaks in the transportation of natural gas and crude oil. Infrared spectroscopy is an important analysis method in the recycling process of household waste plastics , and

1750-400: Is known as corrensite , R1 illite-smectite is rectorite . X-ray rf(001) is the spacing between layers in nanometers, as determined by X-ray crystallography. Glycol (mg/g) is the adsorption capacity for glycol, which occupies the interlayer sites when the clay is exposed to a vapor of ethylene glycol at 60 °C (140 °F) for eight hours. CEC is the cation exchange capacity of

1820-855: Is less practical in the infrared than the FTIR method. One reason that FTIR is favored is called " Fellgett's advantage " or the "multiplex advantage": The information at all frequencies is collected simultaneously, improving both speed and signal-to-noise ratio . Another is called "Jacquinot's Throughput Advantage": A dispersive measurement requires detecting much lower light levels than an FTIR measurement. There are other advantages, as well as some disadvantages, but virtually all modern infrared spectrometers are FTIR instruments. Various forms of infrared microscopy exist. These include IR versions of sub-diffraction microscopy such as IR NSOM , photothermal microspectroscopy , Nano-FTIR and atomic force microscope based infrared spectroscopy (AFM-IR). Infrared spectroscopy

1890-424: Is more useful. For example, if the sample is a dilute solute dissolved in water in a beaker, then a good reference measurement might be to measure pure water in the same beaker. Then the reference measurement would cancel out not only all the instrumental properties (like what light source is used), but also the light-absorbing and light-reflecting properties of the water and beaker, and the final result would just show

1960-458: Is not the only method of studying molecular vibrational spectra. Raman spectroscopy involves an inelastic scattering process in which only part of the energy of an incident photon is absorbed by the molecule, and the remaining part is scattered and detected. The energy difference corresponds to absorbed vibrational energy. The selection rules for infrared and for Raman spectroscopy are different at least for some molecular symmetries , so that

2030-452: Is often interpreted as having two regions. In the functional region there are one to a few troughs per functional group. In the fingerprint region there are many troughs which form an intricate pattern which can be used like a fingerprint to determine the compound. For many kinds of samples, the assignments are known, i.e. which bond deformation(s) are associated with which frequency. In such cases further information can be gleaned about

2100-431: Is only one tetrahedral and one octahedral group in each layer the clay is known as a 1:1 clay. The alternative, known as a 2:1 clay, has two tetrahedral sheets with the unshared vertex of each sheet pointing towards each other and forming each side of the octahedral sheet. Bonding between the tetrahedral and octahedral sheets requires that the tetrahedral sheet becomes corrugated or twisted, causing ditrigonal distortion to

2170-543: Is the measurement of the interaction of infrared radiation with matter by absorption , emission , or reflection . It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. It can be used to characterize new materials or identify and verify known and unknown samples. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) which produces an infrared spectrum . An IR spectrum can be visualized in

Blackjack Formation - Misplaced Pages Continue

2240-414: Is then pressed in a mechanical press to form a translucent pellet through which the beam of the spectrometer can pass. A third technique is the "cast film" technique, which is used mainly for polymeric materials. The sample is first dissolved in a suitable, non- hygroscopic solvent. A drop of this solution is deposited on the surface of a KBr or NaCl cell. The solution is then evaporated to dryness and

2310-449: The CH 2 portion: two stretching modes (ν): symmetric (ν s ) and antisymmetric (ν as ); and four bending modes: scissoring (δ), rocking (ρ), wagging (ω) and twisting (τ), as shown below. Structures that do not have the two additional X groups attached have fewer modes because some modes are defined by specific relationships to those other attached groups. For example, in water,

2380-407: The polymerization of RNA in aqueous solution from nucleotide monomers, and the formation of membranes from lipids. In 1998, Hyman Hartman proposed that "the first organisms were self-replicating iron-rich clays which fixed carbon dioxide into oxalic acid and other dicarboxylic acids . This system of replicating clays and their metabolic phenotype then evolved into the sulfide rich region of

2450-993: The 1930s with advancements in the x-ray diffraction (XRD) technique indispensable to deciphering their crystal lattice. Clay particles were found to be predominantly sheet silicate (phyllosilicate) minerals, now grouped together as clay minerals. Their structure is based on flat hexagonal sheets similar to those of the mica group of minerals. Standardization in terminology arose during this period as well, with special attention given to similar words that resulted in confusion, such as sheet and plane. Because clay minerals are usually (but not necessarily) ultrafine-grained, special analytical techniques are required for their identification and study. In addition to X-ray crystallography, these include electron diffraction methods, various spectroscopic methods such as Mössbauer spectroscopy , infrared spectroscopy , Raman spectroscopy , and SEM - EDS or automated mineralogy processes. These methods can be augmented by polarized light microscopy ,

2520-460: The IR Biotyper for food microbiology. Infrared spectroscopy exploits the fact that molecules absorb frequencies that are characteristic of their structure . These absorptions occur at resonant frequencies , i.e. the frequency of the absorbed radiation matches the vibrational frequency. The energies are affected by the shape of the molecular potential energy surfaces , the masses of the atoms, and

2590-442: The IR beam These devices are selected on the basis of their transparency in the region of interest and their resilience toward the sample. Gaseous samples require a sample cell with a long pathlength to compensate for the diluteness. The pathlength of the sample cell depends on the concentration of the compound of interest. A simple glass tube with length of 5 to 10 cm equipped with infrared-transparent windows at both ends of

2660-503: The absorption of a photon leading to a direct transition from the ground state to the second excited vibrational state ( v = 2). Such a band appears at approximately twice the energy of the fundamental band for the same normal mode. Some excitations, so-called combination modes , involve simultaneous excitation of more than one normal mode. The phenomenon of Fermi resonance can arise when two modes are similar in energy; Fermi resonance results in an unexpected shift in energy and intensity of

2730-440: The applications of clays include drug delivery, tissue engineering, and bioprinting. Clay minerals can be incorporated in lime-metakaolin mortars to improve mechanical properties. Electrochemical separation helps to obtain modified saponite-containing products with high smectite-group minerals concentrations, lower mineral particles size, more compact structure, and greater surface area. These characteristics open possibilities for

2800-547: The associated vibronic coupling . In particular, in the Born–Oppenheimer and harmonic approximations (i.e. when the molecular Hamiltonian corresponding to the electronic ground state can be approximated by a harmonic oscillator in the neighbourhood of the equilibrium molecular geometry ), the resonant frequencies are associated with the normal modes of vibration corresponding to the molecular electronic ground state potential energy surface. Thus, it depends on both

2870-571: The average pH level of 7.1 is reached at 30% of the pulp added and an experimental site with perennial grasses proved the efficacy of the technique. Moreover, the reclamation of disturbed lands is an integral part of the social and environmental responsibility of the mining company and this scenario addresses the community necessities at both local and regional levels. The results of glycol adsorption, cation exchange capacity, X-ray diffraction, differential thermal analysis, and chemical tests all give data that may be used for quantitative estimations. After

Blackjack Formation - Misplaced Pages Continue

2940-416: The bands etc. The infrared spectrum of a sample is recorded by passing a beam of infrared light through the sample. When the frequency of the IR matches the vibrational frequency of a bond or collection of bonds, absorption occurs. Examination of the transmitted light reveals how much energy was absorbed at each frequency (or wavelength). This measurement can be achieved by scanning the wavelength range using

3010-600: The character or quantity of a particular bond are assessed by measuring at a specific frequency over time. Instruments can routinely record many spectra per second in situ, providing insights into reaction mechanism (e.g., detection of intermediates) and reaction progress. Infrared spectroscopy is utilized in the field of semiconductor microelectronics: for example, infrared spectroscopy can be applied to semiconductors like silicon , gallium arsenide , gallium nitride , zinc selenide , amorphous silicon, silicon nitride , etc. Another important application of infrared spectroscopy

3080-482: The clay. K 2 O (%) is the percent content of potassium oxide in the clay. DTA describes the differential thermal analysis curve of the clay. The clay hypothesis for the origin of life was proposed by Graham Cairns-Smith in 1985. It postulates that complex organic molecules arose gradually on pre-existing, non-organic replication surfaces of silicate crystals in contact with an aqueous solution. The clay mineral montmorillonite has been shown to catalyze

3150-433: The dwarf planet Ceres , asteroid 101955 Bennu , and comet Tempel 1 , as well as Jupiter's moon Europa . Like all phyllosilicates, clay minerals are characterised by two-dimensional sheets of corner-sharing SiO 4 tetrahedra or AlO 4 octahedra. The sheet units have the chemical composition (Al, Si) 3 O 4 . Each silica tetrahedron shares three of its vertex oxygen ions with other tetrahedra, forming

3220-454: The essential features are effectively hidden under the total spectrum. Extraction of the essential features therefore requires advanced statistical methods such as machine learning and deep-neural networks. The potential of this technique for bacteria classification have been demonstrated for differentiation at the genus, species and serotype taxonomic levels, and it has also been shown promising for antimicrobial susceptibility testing, which

3290-407: The film formed on the cell is analysed directly. Care is important to ensure that the film is not too thick otherwise light cannot pass through. This technique is suitable for qualitative analysis. The final method is to use microtomy to cut a thin (20–100 μm) film from a solid sample. This is one of the most important ways of analysing failed plastic products for example because the integrity of

3360-897: The formation support a reconstruction of the supercontinent , Rodinia , in which Australia was a source of sediments for southwestern Laurentia . The formation was first named by D.E. Livingston in 1969 for outcroppings 30 kilometers (20 mi) in the Blackjack Mountains, Arizona . Michael F. Doe and coinvestigators proposed removing the Yankee Joe and Blackjack into the Yankee Joe Group. Argillaceous Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin , Al 2 Si 2 O 5 ( OH ) 4 ), sometimes with variable amounts of iron , magnesium , alkali metals , alkaline earths , and other cations found on or near some planetary surfaces . Clay minerals form in

3430-454: The hexagonal array, and the octahedral sheet is flattened. This minimizes the overall bond-valence distortions of the crystallite. Depending on the composition of the tetrahedral and octahedral sheets, the layer will have no charge or will have a net negative charge. If the layers are charged this charge is balanced by interlayer cations such as Na or K or by a lone octahedral sheet. The interlayer may also contain water. The crystal structure

3500-425: The hot spring acquiring the ability to fix nitrogen . Finally phosphate was incorporated into the evolving system which allowed the synthesis of nucleotides and phospholipids." The structural and compositional versatility of clay minerals gives them interesting biological properties. Due to disc-shaped and charged surfaces, clay interacts with a range of drugs, protein, polymers, DNA, or other macromolecules. Some of

3570-452: The manufacture of high-quality ceramics and heavy-metal sorbents from saponite-containing products. Furthermore, tail grinding occurs during the preparation of the raw material for ceramics; this waste reprocessing is of high importance for the use of clay pulp as a neutralizing agent, as fine particles are required for the reaction. Experiments on the histosol deacidification with the alkaline clay slurry demonstrated that neutralization with

SECTION 50

#1732891212643

3640-418: The measurements of photon life-times (and not the laser intensity) makes it needless for any calibration and comparison with a reference Some instruments also automatically identify the substance being measured from a store of thousands of reference spectra held in storage. Fourier transform infrared (FTIR) spectroscopy is a measurement technique that allows one to record infrared spectra. Infrared light

3710-607: The molecule is symmetrical, e.g. N 2 , the band is not observed in the IR spectrum, but only in the Raman spectrum . Asymmetrical diatomic molecules, e.g. carbon monoxide ( CO ), absorb in the IR spectrum. More complex molecules have many bonds, and their vibrational spectra are correspondingly more complex, i.e. big molecules have many peaks in their IR spectra. The atoms in a CH 2 X 2 group, commonly found in organic compounds and where X can represent any other atom, can vibrate in nine different ways. Six of these vibrations involve only

3780-432: The molecule, are much smaller than the movements of the lighter H atoms. The simplest and most important or fundamental IR bands arise from the excitations of normal modes, the simplest distortions of the molecule, from the ground state with vibrational quantum number v = 0 to the first excited state with vibrational quantum number v = 1. In some cases, overtone bands are observed. An overtone band arises from

3850-525: The nature of the bonds and the mass of the atoms that are involved. Using the Schrödinger equation leads to the selection rule for the vibrational quantum number in the system undergoing vibrational changes: △ v = ± 1 {\displaystyle \bigtriangleup v=\pm 1} The compression and extension of a bond may be likened to the behaviour of a spring , but real molecules are hardly perfectly elastic in nature. If

3920-400: The presence of water and have been important to life, and many theories of abiogenesis involve them. They are important constituents of soils , and have been useful to humans since ancient times in agriculture and manufacturing . Clay is a very fine-grained geologic material that develops plasticity when wet, but becomes hard, brittle and non–plastic upon drying or firing . It is

3990-438: The properties of the solute (at least approximately). A common way to compare to a reference is sequentially: first measure the reference, then replace the reference by the sample and measure the sample. This technique is not perfectly reliable; if the infrared lamp is a bit brighter during the reference measurement, then a bit dimmer during the sample measurement, the measurement will be distorted. More elaborate methods, such as

4060-452: The quantities of organic matter, carbonates, free oxides, and nonclay minerals have been determined, the percentages of clay minerals are estimated using the appropriate glycol adsorption, cation exchange capacity, K20, and DTA data. The amount of illite is estimated from the K20 content since this is the only clay mineral containing potassium. Argillaceous rocks are those in which clay minerals are

4130-410: The relative molecular or electromagnetic properties. Infrared spectroscopy is a simple and reliable technique widely used in both organic and inorganic chemistry, in research and industry. It is used in quality control, dynamic measurement, and monitoring applications such as the long-term unattended measurement of CO 2 concentrations in greenhouses and growth chambers by infrared gas analyzers. It

4200-581: The requirement of water, clay minerals are relatively rare in the Solar System , though they occur extensively on Earth where water has interacted with other minerals and organic matter . Clay minerals have been detected at several locations on Mars , including Echus Chasma , Mawrth Vallis , the Memnonia quadrangle and the Elysium quadrangle . Spectrography has confirmed their presence on celestial bodies including

4270-411: The rocking, wagging, and twisting modes do not exist because these types of motions of the H atoms represent simple rotation of the whole molecule rather than vibrations within it. In case of more complex molecules, out-of-plane (γ) vibrational modes can be also present. These figures do not represent the " recoil " of the C atoms, which, though necessarily present to balance the overall movements of

SECTION 60

#1732891212643

4340-417: The sample and a "reference". This step controls for a number of variables, e.g. infrared detector , which may affect the spectrum. The reference measurement makes it possible to eliminate the instrument influence. The appropriate "reference" depends on the measurement and its goal. The simplest reference measurement is to simply remove the sample (replacing it by air). However, sometimes a different reference

4410-404: The solid is preserved. In photoacoustic spectroscopy the need for sample treatment is minimal. The sample, liquid or solid, is placed into the sample cup which is inserted into the photoacoustic cell which is then sealed for the measurement. The sample may be one solid piece, powder or basically in any form for the measurement. For example, a piece of rock can be inserted into the sample cup and

4480-473: The spectra unreadable without this computer treatment). Solid samples can be prepared in a variety of ways. One common method is to crush the sample with an oily mulling agent (usually mineral oil Nujol ). A thin film of the mull is applied onto salt plates and measured. The second method is to grind a quantity of the sample with a specially purified salt (usually potassium bromide ) finely (to remove scattering effects from large crystals). This powder mixture

4550-419: The spectrum measured from it. A useful way of analyzing solid samples without the need for cutting samples uses ATR or attenuated total reflectance spectroscopy. Using this approach, samples are pressed against the face of a single crystal. The infrared radiation passes through the crystal and only interacts with the sample at the interface between the two materials. It is typical to record spectrum of both

4620-437: The term reichweite , which is German for range or reach. Literature articles will refer to an R1 ordered illite-smectite, for example. This type would be ordered in an illite-smectite-illite-smectite (ISIS) fashion. R0 on the other hand describes random ordering, and other advanced ordering types are also found (R3, etc.). Mixed layer clay minerals which are perfect R1 types often get their own names. R1 ordered chlorite-smectite

4690-402: The tetrahedral sheet also forms part of one side of the octahedral sheet, but an additional oxygen atom is located above the gap in the tetrahedral sheet at the center of the six tetrahedra. This oxygen atom is bonded to a hydrogen atom forming an OH group in the clay structure. Clays can be categorized depending on the way that tetrahedral and octahedral sheets are packaged into layers . If there

4760-438: The tube can be used for concentrations down to several hundred ppm. Sample gas concentrations well below ppm can be measured with a White's cell in which the infrared light is guided with mirrors to travel through the gas. White's cells are available with optical pathlength starting from 0.5 m up to hundred meters. Liquid samples can be sandwiched between two plates of a salt (commonly sodium chloride , or common salt, although

4830-406: The two methods are complementary in that they observe vibrations of different symmetries. Another method is electron energy loss spectroscopy (EELS), in which the energy absorbed is provided by an inelastically scattered electron rather than a photon. This method is useful for studying vibrations of molecules adsorbed on a solid surface. Recently, high-resolution EELS (HREELS) has emerged as

4900-658: Was originally assigned to the Hess Canyon Group , in which it overlies the Yankee Joe Formation . It is overlain in turn across an unconformity by the Apache Group . The formation is interpreted as a nearshore fluvial and tidal deposit. The formation was deposited in a large basin, the Yankee Joe — Defiance basin, which is contemporaneous with the Picuris basin . Detrital zircon age spectrums and isotope ratios from

#642357