Showing papers on "Absorption spectroscopy published in 1973"
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26 Jan 1973
TL;DR: In this article, a compilation of the molecular spectroscopic parameters for a number of infrared-active molecules occurring naturally in the terrestrial atmsophere is presented, including water vapor, carbon dioxide, ozone, nitrous oxide, carbon monoxide, methane, and oxygen.
Abstract: : The report describes a compilation of the molecular spectroscopic parameters for a number of infrared-active molecules occurring naturally in the terrestrial atmsophere. The following molecules are included in this compilation: water vapor; carbon dioxide; ozone; nitrous oxide; carbon monoxide; methane; and oxygen. The spectral region covered extends from less than 1 micrometer to the far infrared, and data are presented on more than 100, 000 spectral lines. The parameters included in the compilation for each line are: frequency, intensity, half-width, energy of the lower state of the transition, vibrational and rotational identifications of the upper and lower energy states, an isotopic identification, and a molecular identification. A discussion is provided separately for each molecular species, indicating the sources and accuracy of the data and a general discussion of how the data were obtained.
376 citations
336 citations
TL;DR: Azo compounds are characterized by a low energy 1 n,π* electronic state, which gives rise to a weak band at long wavelengths in the absorption spectrum as discussed by the authors, and coupling of this state with other low-lying molecular states is responsible for the high intensity of the "azo band" compared to other forbidden transitions, for its lack of vibrational structure, and for the inability of nearly all organic azo compounds to fluoresce.
Abstract: Azo compounds are characterized by a low-energy 1(n,π*) electronic state, which gives rise to a weak band at long wavelengths in the absorption spectrum. Coupling of this state with other low-lying molecular states is responsible for the high intensity of the “azo band” compared to other forbidden transitions, for its lack of vibrational structure, and for the inability of nearly all organic azo compounds to fluoresce.
278 citations
TL;DR: The fabrication of extremely low-loss glass optical waveguide, having as little as 4 dB/km total attenuation, has allowed interpretation of the absorption spectrum to a much greater degree than previously possible as discussed by the authors.
Abstract: The fabrication of an extremely‐low‐loss glass optical waveguide, having as little as 4 dB/km total attenuation, has allowed interpretation of the absorption spectrum to a much greater degree than previously possible It is shown that, beyond about 700 nm, intrinsic ultraviolet absorption will have no effect Between 700 and 1100 nm, all absorption can be accounted for on the basis of OH to within ±07 dB/km Marked reduction of the water content will leave the scattering as the major loss mechanism, thereby permitting total attenuations of about 2 dB/km
246 citations
TL;DR: In this paper, an argon discharge source is used to estimate the underlying continuum absorption in the banded region of I2 in the region 4200-8000 A. The A[1u(3Π)]← X absorption is found to be a factor of 2 stronger than previous estimates with a peak extinction of 41 liter mole−1 · cm−1 at 6730 A.
Abstract: New extinction coefficient measurements are reported for I2 in the region 4200–8000 A. An argon discharge source is used to estimate the underlying continuum absorption in the banded region. Together with other work these results locate the maximum in the 1 u(1Π) ← X[O+g(1Σ)] absorption at 4985 A with a peak extinction of 200 liter mole−1 · cm−1. From the shape of the spectrum the 1u (1Π) potential curve behaves as r−9 in the region of strong absorption. The A[1u(3Π)]← X absorption is found to be a factor of 2 stronger than previous estimates with a peak extinction of 41 liter mole−1 · cm−1 at 6730 A. Earlier indications of a linear dependence of the dipole strength on r centroid for the B [O+u(3Π)]↔ X system are supported in this study. Spectroscopic data for the B↔ X transition are reviewed and new spectroscopic constants recommended for the B state.
245 citations
TL;DR: In this paper, numerical corrections are made to previous values for the power absorption coefficient and some common errors noted, and common errors are noted for power absorption coefficients in terms of the power absorbed coefficient.
Abstract: Numerical corrections are made to previous values for the power absorption coefficient and some common errors noted.
242 citations
TL;DR: The photoelectron and vacuum ultraviolet absorption spectra (200-120 nm) of CF3Cl, CF3Br, CF2HCl and CFHCl2 are reported and discussed in this paper.
Abstract: The photoelectron and vacuum ultraviolet absorption spectra (200–120 nm) of CF3Cl, CF3Br, CF2HCl, CFH2Cl, CFHCl2, CF2Cl2, and CFCl3 are reported and discussed. The lowest ionization potentials belong to the chlorine or bromine lone pair orbitals, the next highest ones to the bonding orbitals of mainly C–Cl or C–Br character. In the absorption spectra the lowest freuqency bands are due to weak valence‐shell type transitions. At higher freuqencies we find much stronger Rydberg type bands related to the first ionization potential. All absorption bands up to 84 000 cm−1 depart from chlorine or bromine lone pair orbitals. Some of the bands exhibit vibrational fine structure. An increase in the number of the fluorine atoms causes a shift to either higher or lower energies of the ionization potentials belonging to orbitals of mainly C–H or C–Cl character according to the cases while the lone pair ionization potentials and the absorption spectra shift to higher energies in all cases.
167 citations
TL;DR: In this paper, a cw dye laser system frequency stabilized to a high-finesse optical reference cavity is described, where the laser frequency is servo controlled to the cavity resonance with residual fluctuations less than 50 kHz for short times (20 μsec) and 100 Hz for long times (10 sec).
Abstract: A cw dye laser system frequency stabilized to a high‐finesse optical reference cavity is described. Laser frequency is servo controlled to the cavity resonance with residual fluctuations less than 50 kHz for short times (20 μsec) and 100 Hz for long times (10 sec). Drift in absolute laser frequency of about 1.5 MHz/min is observed due to drift of the unstabilized reference cavity. A saturated absorption spectrum of I2 obtained with this system is shown.
154 citations
TL;DR: A preliminary survey of electronic absorption spectra of clay minerals reveals the utility of u.v. spectroscopy in the elucidation of structural, physical, and chemical properties of such systems as mentioned in this paper.
Abstract: A preliminary survey of electronic absorption spectra of clay minerals reveals the utility of u.v.-visible spectroscopy in the elucidation of structural, physical, and chemical properties of such systems. Spectra, which were obtained in the suspension, film, and single crystal states (where applic- able), are interpreted in terms of iron-associated transitions. Microcrystalline clay minerals typically show Fe(lll) in octahedral oxo-ligand geometry whereas mica-type minerals may show a range of iron species, including octahedral Fe(III), tetrahedral Fe(IlI), and octahedral Fe(I1). Iron affects the local site geometry and in "high iron" minerals may dictate layer geometry and subsequently the crystalline form.
146 citations
TL;DR: In this article, the electronic emission and absorption spectrum of HF has been photographed at high resolution with a 10m grating spectrograph and the dissociation energy has been found to be D0(HF)
Abstract: The electronic emission and absorption spectrum of HF has been photographed at high resolution with a 10 m grating spectrograph. The emission, which extends from 2670 to 1480 A, consists entirely of bands of the B1Σ+–X1Σ+ (previously denoted as the V1Σ+–X1Σ+)system. From the analysis of 51 bands of the emission spectrum, constants of the vibrational levels of the X state from ν = 7 and 19 and of the B state from ν = 0 to 10 have been determined. The dissociation energy of HF has been found to be D0(HF) = 47 333 ± 60 cm−1. In the absorption spectrum, 56 bands of the B–X system have been identified. Vibrational levels of the B state between ν = 14 and 26 were found to be well behaved and readily analyzed, but levels between ν = 26 and 73 were found to be highly perturbed. Rydberg–Klein–Rees potential curves have been calculated for the B and X states and it is shown that at large internuclear distances the bonding of the B state is almost entirely ionic.
141 citations
TL;DR: In this paper, the effect of 300-keV proton bombardment and subsequent annealing on the optical absorption and electrical resistivity of bulk p-type GaAs has been studied.
Abstract: The effect of 300‐keV proton bombardment and subsequent annealing on the optical absorption and electrical resistivity of bulk p‐type (p=2×1018 and 1.4×1019 cm−3) GaAs has been studied. Proton doses were in the range 1013−1017 cm−2. It is found that bombardment‐induced optical absorption increases monotonically, but sublinearly, with proton dose. The shape of the optical transmission spectrum indicates that bombardment creates a distribution of energy levels extending into the forbidden gap. Activation energies for annealing of the optical absorption have been determined from isothermal annealing data and range from ∼1.5 to ∼3.4 eV, which indicates that at least two kinds of defects are involved. Current‐voltage measurements show that the average electrical resistivity of the bombarded layers goes through a maximum at ∼2.5×105 Ω cm at a proton dose of ∼3×1015 cm−2. It is shown that annealing can eliminate the bombardment‐induced optical absorption while still retaining a high electrical resistivity. The o...
TL;DR: In this paper, the van der Waals dimer Kr2 has been photographed in the region 1050-1260 A by a 6.65 m spectrograph with the argon continuum as background source.
Abstract: The vacuum ultraviolet absorption spectrum of the van der Waals dimer Kr2 has been photographed in the region 1050–1260 A by a 6.65 m spectrograph with the argon continuum as background source. Eight band systems, four well‐developed and four rather fragmented, are observed. Vibronic analyses of the former four systems reveal that their upper states are correlated to separated atom limits in which one Kr atom is excited to various levels of configuration 4p55s. Upper molecular state designations and dissociation limits are discussed. The four fragmented band systems are energetically close to various KrI levels of configuration 4p55p. A similar study of a mixture of argon and krypton yields five groups of diffuse bands attributed to ArKr; two of these band groups are close to KrI resonance lines. The ground electronic state of Kr2 supports 16 bound vibrational levels of which nine (ν″ = 0–8) are involved in the observed vibronic structure and the other seven inferred from an extrapolation procedure based ...
TL;DR: In this article, the authors describe the generation of a continuum which has a time duration equal to or less than the picosecond pulse which generates it, and the spectrum of the continuum is several thousand wavenumbers in width.
TL;DR: In this article, the authors measured the absorption coefficient of a number of potential i.r.t. laser window materials and found that the absorption coefficients of LiF, CaF2, BaF2 and SrF2 all decrease exponentially with increasing wavelength.
TL;DR: In this article, the rate constants for quenching of N2 A by ethane exhibit a strong increase with a rising vibrational quantum number, indicating strongly a collision induced intersystem crossing with the N2 B3Πg state.
Abstract: Following the excitation of nitrogen and nitrogen/additive mixtures by single electron pulses the metastable nitrogen A3Σu+ is detected in its vibrational levels v=0–7 by absorption spectroscopy. The additives are ethylene, ethane, and NO. In pure nitrogen the prevailing process is a vibration‐vibration (V‐V) energy transfer process of the N2 A, v≥2 with Δv=2 to groundstate nitrogen. The rate constants increase with higher quantum numbers i.e., improving energy resonance up to a limiting collisional efficiency for this process of 10−2. The kinetic behavior of the vibrational states v=5, 6, 7 indicates strongly a collision induced intersystem crossing with the N2 B3Πg state. The rate constants for quenching of N2 A by ethane exhibit a strong increase with rising vibrational quantum number. Ethylene is generally more reactive and shows no strong dependence on the vibrational level. This is interpreted as a fast quenching of the electronic state by ethylene. While this latter process is relatively slow with ...
TL;DR: In this article, the authors utilized the techniques of picosecond spectroscopy to study the localization of an excess electron in water, which was generated by photoionization of the ferrocyanide anion in aqueous solutions at 2650 A.
Abstract: We have utilized the techniques of picosecond spectroscopy to study the localization of an excess electron in water. Quasifree electrons were generated by the photoionization of the ferrocyanide anion in aqueous solutions at 2650 A. Time resolved absorption of the localized electron was monitored continuously from 1.06 μ to 5300 A, while time and energy resolved absorption was monitored in the range 3100–9000 A by a broad continuum of picosecond duration. Optical absorption of the initially localized electron in the infrared (1.06 μ) is observed within 2 psec after the generation of the quasifree electron. The optical absorption band evolves in time, shifting from lower to higher energies, and the ``normal'' absorption of the hydrated electron is developed in ∼4 psec.
TL;DR: In this paper, a point-ion calculation was performed for the F + center in α-Al 2 O 3 (one electron in an O 2− vacancy) and optical transitions were predicted at 2·26, 3·39 and 5·15 eV.
TL;DR: In this article, the optical absorption spectrum of the solvated electron has been determined by pulse radiolysis in pure liquid ethers: tetrahydrofuran, methyltetrahydron, diethyl ether, dimethoxyethane, diglyme, triglyme and tetraglyme.
Abstract: The optical absorption spectrum of the solvated electron has been determined by pulse radiolysis in the pure liquid ethers: tetrahydrofuran, methyltetrahydrofuran, diethyl ether, dimethoxyethane, diglyme, triglyme, and tetraglyme. The absorption maxima are at 4720, 4650, 4350, 4880, 5220, 5440, and 5580 cm−1, respectively. The half‐widths of the bands have also been measured. The oscillator strength, determined for the first four ethers is approximately unity. The absorption bands have been determined in binary solutions with ethylenediamine and for tetrahydrofuran‐water over the entire concentration range. Calculations using a recent form of a cavity‐continuum model have been compared with the experimental results. The model shows agreement with the experimental values for the transition energy for an effective cavity radius of about 4 A and a coordination number of 6 or 8. Kinetics for the attachment of solvated electrons to pyrene and for the reaction of the solvated electron with the solvent counterio...
TL;DR: A new combination technique of using both dual-wavelength and opalglas methods for scanning translucent biological samples was applied to leaves of terrestrial plants in order to observe their absorption changes by irradiation and the action spectra for the absorption changes.
Abstract: A new combination technique of using both dual-wavelength and opalglas methods for scanning translucent biological samples was applied to leaves of terrestrial plants in order to observe their absorption changes by irradiation and the action spectra for the absorption changes. The measurements of true absorption, free from various effects of scattering, by this technique showed an increase of absorption by weak blue light and a decrease of absorption by strong blue light for almost all of the leaves of 20 plant species examined. These weak- and strong-light responses in absorption were reversible. The fractional increase and decrease of absorbance at 678 nm by weak and strong light were highest, +20% and -31%, for leaves of Begonia semperflorens Link et Otto, and +12% and -13% for leaves of foxtail, Setaria viridis (L.) Beauv., the species examined in further experiments. The response to strong light proceeded to completion earlier than did that to weak light. The strong-light response could be observed separately from the weak-light response by using a leaf pre-irradiated with weak blue light. The responses were measured as a function of light intensity by scanning a single leaf irradiated locally at different intensities, and the action spectra for these responses were measured by scanning a leaf irradiated locally at different wavelengths but at identical intensities. The action spectra for these opposite responses were similar, and showed a band at 450 nm with shoulders but no band in the red region. Microscopic observations of chloroplasts in leaves during irradiation indicated that these changes in absorption are mostly due to rearrangements of chloroplasts in cells caused by irradiation.
TL;DR: In this article, the defect concentration in CDR gradually increases with the increasing of irradiation dose, and when defect concentration achieves some critical value CDR transforms sharply to an amorphous state.
Abstract: Amorphization of silicon single crystals during different mass 80 keV ions bombardment (B+, C+, Ne+, Ar+, Sb+) has been studied by means of three independent techniques, (a) ir absorption at 1.8 μ wave length (divacancy absorption), (b) ir reflection near a fundamental absorption edge, and (c) electron microscopy and fast electron diffraction. Irradiation was carried out at room temperature. From the analysis of data obtained it can be concluded that two types of disordered regions arise during ion bombardment, (a) amorphous regions (AR) and (b) disordered, but still possessing crystalline structure regions, which we call the crystalline disordered regions (CDR). In CDR the defect concentration is so high that divacancies do not appear. The defect concentration in CDR gradually increases with the increasing of irradiation dose. When the defect concentration achieves some critical value CDR transforms sharply to an amorphous state. Such amorphization mechanism prevails for light ions. For heavy io...
TL;DR: In this paper, the absorption spectra and extinction coefficients for triplet-triplet and photodecomposition product absorption in Rhodamine 6G-ethanol solution are reported.
TL;DR: In this paper, a thorough examination of the room temperature emission properties of a large number of diamagnetic closed shell metal complexes exhibiting luminescence localized in the ligand was made, and the results showed that heavy atom perturbation of the spin selection rule is systematically affecting the intersystem crossing rate.
TL;DR: In this article, the first order Raman spectra and far infrared absorption spectra of GaS and GaSe have been investigated and interpreted and a correspondence is drawn between the observed vibrational modes of the two crystals and a Raman active polar longitudinal mode has been identified in GaSe.
TL;DR: In this paper, the ESR spectrometer was operated with no field modulation, and spectra were presented as absorption curves, showing evidence of a nonequilibrium population of spin levels with the low field lines of the latter two radicals observed in emission.
Abstract: ESR experiments with time resolution on the order of 1 μsec have been carried out upon aqueous solutions during repetitive pulse radiolysis with a 2.8 MeV electron beam. The ESR spectrometer was operated with no field modulation, and spectra were presented as absorption curves. The radicals ĊH(CO2−)2, ĊH2CO2−, and hydroxycyclohexadienyl, formed in each case by reactions of OH, were studied and each spectrum showed evidence of a nonequilibrium population of spin levels, with the low field lines of the latter two radicals observed in emission. For ĊH2CO2− this emission persists for ∼ 50 μsec. The observed signals are described by enhancement factors V (fractional excess signal) of 0.23, 3.1, and 12.3, respectively. From the short spin relaxation times (1.4 μsec was measured for ĊH2CO2−) it is evident that emission existing at times much greater than this relaxation period must be the result of a continuous regeneration of the population differences by the radical‐radical reactions. The form of the kinetic e...
TL;DR: In this article, a krypton ion laser operating at 6470°A excites strong resonance fluorescence in nitrogen dioxide gas, and the fluorescence bands have a parallel structure (ΔK = 0) and are assigned to the electronical...
Abstract: A krypton ion laser operating at 6470 A excites strong resonance fluorescence in nitrogen dioxide gas. The fluorescence bands have "parallel" structure (ΔK = 0) and are assigned to the electronical...
TL;DR: In this paper, the dispersion of refractive index, polarizability, and dielectric permeability of damped oscillators is calculated based on the semiclassical model of oscillators and a least squares fit is used to determine oscillator strengths and damping factors.
Abstract: Based on the semiclassical model of damped oscillators, a procedure is developed for the calculation of the dispersion of refractive index, polarizability, and dielectric permeability, which are treated as complex quantities. Using experimental values of refractive indices and employing the frequencies of strong absorption bands, a least squares fit is used to determine oscillator strengths and damping factors. The absorption coefficient and the imaginary part of the refractive index are also calculated at the corresponding wavelengths. The procedure is applied for the cases of water, hydrogen, and oxygen in both the liquid and gaseous states and for gaseous carbon dioxide, and a good agreement is obtained between calculated and observed values of refractive indices. Results are also compared with those of previous calculations. Calculated absorption coefficients agree well with experimental values in the region of absorption bands. The calculated values of oscillator strengths and damping factors are dis...
01 Dec 1973
TL;DR: In this paper, a table of wavelengths, statistical weights, and excitation energies for 944 atomic spectral lines in 221 multiplets whose lower energy levels lie below 0.275 eV was given.
Abstract: A table of wavelengths, statistical weights, and excitation energies is given for 944 atomic spectral lines in 221 multiplets whose lower energy levels lie below 0.275 eV. Oscillator strengths were adopted for 635 lines in 155 multiplets from the available experimental and theoretical determinations. Radiation damping constants also were derived for most of these lines. This table contains the lines most likely to be observed in absorption in interstellar clouds, circumstellar shells, and the clouds in the direction of quasars where neither the particle density nor the radiation density is high enough to populate the higher levels. All ions of all elements from hydrogen to zinc are included which have resonance lines longward of 912 A, although a number of weaker lines of neutrals and first ions have been omitted.