Showing papers on "Absorption spectroscopy published in 1969"
TL;DR: In this paper, a transparent plate model with rough plane-parallel surfaces was used to model isotropic light interaction with compact corn leaf, using transparent plate with rough surface.
Abstract: Diffuse isotropic light interaction with compact corn leaf, using transparent plate model with rough plane-parallel surfaces
274 citations
210 citations
209 citations
TL;DR: In this article, the effect is treated within a simple model by the methods of perturbation theory and it is shown that even to lowest order one must sum the parquet diagrams, in close analogy with the Abrikosov theory of the Kondo effect.
Abstract: X-ray emission and absorption spectra in metals may display singularities near the Fermi-level threshold. These singularities, predicted by Mahan, are due to final-state interactions between conduction electrons and the localized disturbance created by the x ray. The effect is treated within a simple model by the methods of perturbation theory. It is shown that even to lowest order one must sum the so-called parquet diagrams, in close analogy with the Abrikosov theory of the Kondo effect. Mahan's prediction is confirmed, and its validity discussed. Various secondary effects which could blur the singularity are analyzed.
180 citations
TL;DR: It is found that the transfer rate is proportional to J, as predicted by Förster's theory, and the results bear on the potential use of this energy transfer process to measure distances in biological macromolecules.
Abstract: Singlet-singlet energy transfer kinetics dependence on emission and absorption spectra overlap via dipole-dipole interaction
164 citations
TL;DR: In this paper, the rotational and vibrational band structure of carbon monoxide absorption in vacuum UV region was discussed, and the fourth positive CO system was observed in absorption of vacuum UV regions.
Abstract: Fourth positive carbon monoxide system observed in absorption in vacuum UV region, discussing rotational and vibrational band structure
151 citations
TL;DR: In this article, the 0-0 bands at 1474 A and 1422 A of the first two members of the nf-X2Π Rydberg series of NO have been observed under high resolution in the absorption spectrum of cold nitric oxide gas.
Abstract: The 0–0 bands at 1474 A and 1422 A of the first two members of the nf–X2Π Rydberg series of NO have been observed under high resolution in the absorption spectrum of cold nitric oxide gas. They sho...
127 citations
125 citations
TL;DR: In this article, the optical properties of seven liquid metals, in the frequency range between 0·77 and 5·0 ev and at temperatures up to 1600°c, were measured by a polarimetric method.
Abstract: Measurements have been made, by a polarimetric method, of the optical properties of seven liquid metals, in the frequency range between 0·77 and 5·0 ev and at temperatures up to 1600°c. For Al the results show no sign of the absorption peak at about 1·5 ev which is observed for the solid and are in rough agreement with the Drude free-electron curves; deviations from these curves may be due to surface contamination, though an attempt to explain them quantitatively in this way is not successful. For Cu, Ag and Au the results at low frequencies suggest that the effective density of conduction electrons, n∗, rises slightly on melting, as is to be expected if the structure of the conduction band is smoothed out; the absorption edges due to excitation of electrons from the d band, however, are scarcely changed at all. For the transition metals Fe, Co and Ni, which lie next to one another in the Periodic Table, the absorption spectra show little in the way of structure; the most notable feature of the r...
123 citations
TL;DR: In this article, high-resolution studies of the absorption spectrum of N2 have been made in the region 1015-795 A. Analyses were given of 25 non-Rydberg bands of the type 1Πu-X1Σg+
Abstract: New high resolution studies of the absorption spectrum of N2 have been made in the region 1015–795 A. Analyses are given of 25 non-Rydberg bands of the type 1Πu–X1Σg+. It is shown that all of these...
115 citations
TL;DR: Jupiter spectrum observations in 2.8-14 micron range, describing absorption strength and brightness temperature, basing analysis on ammonia, methane and hydrogen absorption as discussed by the authors, were used for the analysis.
Abstract: Jupiter spectrum observations in 2.8-14 micron range, describing absorption strength and brightness temperature, basing analysis on ammonia, methane and hydrogen absorption
TL;DR: In this article, the authors calculated the extended x-ray absorption fine structure by treating the ejected photoelectron as a spherical wave which expands in the lattice and is partially scattered by neighbors of the absorbing atom.
Abstract: : The extended x-ray absorption fine structure is calculated by treating the ejected photoelectron as a spherical wave which expands in the lattice and is partially scattered by neighbors of the absorbing atom. The neighboring atoms are treated as point scatterers and the total scattered wave is summed from the waves scattered by each atom. The fine structure is determined from the dipole transition matrix between the initial K-state and the final photoelectron state. Calculations compare favorably with experimental data. (Author)
TL;DR: In this paper, the infrared absorption spectra of photolyzed Ar:CF3F samples include bands which may be assigned to CH, to CF, and to HCF.
Abstract: Upon vacuum‐ultraviolet photolysis of methyl fluoride in an argon or a nitrogen matrix at 14°K, the free radicals CF, HCF, and H2CF are stabilized in sufficient concentration for observation of their infrared absorption spectra. Studies utilizing carbon‐13 and deuterium substitution confirm the identification of these species. Visible‐ultraviolet absorption spectra of photolyzed Ar:CF3F samples include bands which may be assigned to CH, to CF, and to HCF. The reaction of carbon atoms, produced by the photolysis of cyanogen azide isolated in an argon matrix, with HF trapped in the matrix has also been found to lead to the stabilization of sufficient HCF for infrared spectroscopic detection. Reaction of HCF with a second molecule of HF to form CH2F2 also occurs. The force constants and thermodynamic properties of HCF have been calculated, and a partial vibrational assignment is proposed for H2CF. Although these experiments do not determine the primary photodecomposition processes important for methyl fluoride, there is evidence that both H atom and F atom detachment may occur under the conditions of these experiments.
TL;DR: Calculations of the overlap integrals and critical transfer distances involved show that the large fluorescence quenching produced by this binding is consistent with Forster long range energy transfer from tryptophan to absorption bands produced by the metal-protein interaction.
TL;DR: In this paper, the rotational contours of band O (O+-O+ band) at 2938 A and of the band at 2913 A, confirmed as I 1 1 (O−-O− band), in the absorption spectrum of aniline have been analyzed by the method of computer simulation of the contours in which rotational selection rules and excited state rotational constants are included in the input data.
Abstract: Rotational contours of band O (O+-O+ band) at 2938 A and of the band at 2913 A, confirmed as I 1 1 (O−-O− band), in the absorption spectrum of aniline have been analysed by the method of computer simulation of the contours in which rotational selection rules and excited state rotational constants are included in the input data. The observed contours could be reproduced only by using type B selection rules showing that the electronic transition is 1 B 2-1 A 1. The rotational constants of the O+ level of the excited electronic state are: The change in A from the ground to the excited state is the same as in phenol [1] but B increases by much more than in phenol indicating a greater contraction of the molecule along the long in-plane axis in the excited state than is the case in phenol. The rotational constants show that the inertial defect Δ' is −0·27 ± 0·13 u A2 in the O+ level and −0·40±0·13 u A2 in the O− level of the excited electronic state. The value of Δ' for the O+ level suggests an out-of-plane ang...
TL;DR: In this article, the absorption spectrum of the nitrogen molecule in the 30 AA{} region has been studied photographically, using synchrotron radiation from a 1.3-BeV electron synchroron as the background continuum.
Abstract: The absorption spectrum of the nitrogen molecule in the 30 \AA{} region has been studied photographically, using synchrotron radiation from a 1.3-BeV electron synchrotron as the background continuum. A 2-m grazing incidence spectrograph with a glass grating was used to take the absorption spectrum. Discrete structure has been observed near the $K$ edge of nitrogen. On the basis of electron configuration, the absorption data obtained are compared with the optical spectroscopic data of the NO molecule and it is found that the absorption structure is well explained as due to the excitations of a $1s$ electron to outer-shell orbitals of the nitrogen molecule. The energy value of 409.5 \ifmmode\pm\else\textpm\fi{} 0.1 eV is obtained for the $K$ level of the nitrogen molecule.
TL;DR: The vanadium LII,III x-ray emission and absorption spectra (λ∼24 A) from pure metal, oxides, nitride, carbide, and boride have been investigated using a plane-crystal vacuum spectrometer with electron beam excitation and flow-proportional detection as discussed by the authors.
Abstract: The vanadium LII,III x‐ray emission and absorption spectra (λ∼24 A) from pure metal, oxides, nitride, carbide, and boride have been investigated using a plane‐crystal vacuum spectrometer with electron beam excitation and flow‐proportional detection. Emission spectra were studied over a wide range of accelerating voltages and takeoff angles, showing that satellite emission and self‐absorption effects can cause gross distortion in band shapes. A replica of the LII,III absorption spectrum can be constructed solely from emission spectra afflicted with widely different amounts of self‐absorption. The LII,III emission spectra from the oxides and nitride exhibit an anamalous crossover transition from the 2p level of the anion to the LII and LIII levels of vanadium. This transition appears to be related to the degree of anion‐cation orbital overlap and to the electrical properties of the material. Energy shifts of emission bands and absorption edges indicate the charge flow from vanadium to anion in the oxides and nitride. The LIII edges are used to estimate the width of the forbidden gap in V2O5. Oxygen K emission from the oxides exhibits a peculiar dependence on the dispersing crystal used and is also influenced by satellite emission and self‐absorption.
TL;DR: In this article, it was shown that the optical absorption coefficient varies inversely with light intensity, and that if a monochromatic light beam absorbed by a semiconductor generates enough carriers to fill band states up to and including those of the optical transition, then the absorption will be saturated and a condition of transparency should result.
Abstract: If a monochromatic light beam absorbed by a semiconductor generates enough carriers to fill band states up to and including those of the optical transition, the optical absorption will be saturated and a condition of transparency should result. Analysis shows that in this regime the absorption coefficient varies inversely with light intensity.
TL;DR: In this article, a method for the general computation of Zeeman-split line profiles for pure absorption lines (LTE) is described, where the magnetic field vector, the Doppler shift and the line absorption coefficient are allowed to vary arbitrarily with optical depth.
Abstract: For the case of pure absorption lines (LTE) a method is described which enables the general computation of Zeeman-split line profiles. The magnetic field vector, the Doppler shift and the line absorption coefficient is permitted to vary arbitrarily with optical depth. Elliptical birefringence (e.g., Faraday rotation) of the solar atmosphere is taken into account. Some numerical examples are given and some interesting behaviors of the line profiles are discussed.
TL;DR: In this paper, the absorption spectrum of SO radicals produced by flash photolysis of a mixture of COS + O2 + Ar was investigated, and a partial rotational analysis of the previously known bands of the B3Σ−−−X3 Σ− trans...
Abstract: The absorption spectrum of SO radicals produced by flash photolysis of a mixture of COS + O2 + Ar is investigated. A partial rotational analysis of the previously known bands of the B3Σ−–X3Σ− trans...
TL;DR: The absorption spectra of γ-irradiated solutions of naphthalene in glasses at 77 K provide further evidence for the existence of dimer cations (C10H8)+2 as mentioned in this paper.
Abstract: The absorption spectra of γ-irradiated solutions of naphthalene in glasses at 77 K provide further evidence for the existence of dimer cations (C10H8)+2. Results are also presented for several methyl-naphthalenes, pyrene and 1,2-di(1-naphthyl)-ethane in which a weak intra-molecular interaction occurs. Attempts at producing a dimer anion were unsuccessful. Dimer cations of 9-methyl- and 9-bromo-anthrancene were produced by radiolysis of dilute solutions of the di-anthracenes; there appear to be two distinct dimers in this case.
TL;DR: The absorption spectra of γ-irradiated glasses at 77 K containing cyclohexene, butadiene and penta-1,3-diene have been studied in this article.
Abstract: The absorption spectra of γ-irradiated glasses at 77 K containing cyclohexene, butadiene and penta-1,3-diene have been studied. The effects of warming and recooling and of concentration show that the bands can be assigned to monomeric and dimeric radical cations (M+ and M+2). Assignments of the corresponding spectra of a number of olefins obtained by other workers are discussed.
TL;DR: In this article, the bound exciton transitions are described mainly on AgBr:I - together with related cases of AgCl:Br - and AgCl :I -, mirror image like relations are observed between absorption and emission spectra with zero phonon line at the center.
Abstract: Various correlations are observed between absorption and luminescence spectra of silver halides with isoelectronic impurities at low temperature. In Part I, the bound exciton transitions are described mainly on AgBr:I - together with related cases of AgCl:Br - and AgCl:I - . In AgBr:I - , mirror-image like relations are observed between absorption and emission spectra with zero phonon line at the center. Multiphonon structures are observed in both spectra and the energy of coupled phonon is substantially smaller in absorption that in emission. The difference in phonon energies reflects strong binding of excitons with phonons discussed by Toyozawa and Hermanson. In absorption spectra, additional structures are observed and interpreted as creating excitons in higher excited states. In emission, one phonon sidebands are observed reflecting phonon spectrum in pure AgBr. Discussions are also made on temperature variation of absorption spectrum and on asymmetric intensity distribution between absorption and emi...
TL;DR: The absorption spectra of tetrahydrofuran and 1,3-dioxolane at about 0.3 cm−1 resolution were reported in the region of 20−370 cm −1.
Abstract: The absorption spectra of tetrahydrofuran and of 1,3‐dioxolane at about 0.3‐cm−1 resolution are reported in the region of 20–370 cm−1. It is found that dioxolane pseudorotates, and the earlier evidence for the pseudorotation of tetrahydrofuran is confirmed. Both compounds have barriers to pseudorotation of about 50 cm−1. Pseudorotation constants in both the ground and in the first excited radial states are obtained. The spectra show the effects of a considerable number of complex rotation–vibration interactions, which can be understood qualitatively by comparison with the spectra of four‐membered‐ring compounds. The band shapes are explained semiquantitatively using a number of Coriolis terms in the effective Hamiltonian.
TL;DR: The results of experiments allow the identification of particular absorption bands in the 11-cis-retinal spectrum, which are steric hindrance and bend in the system of conjugated double bonds.
Abstract: THE absorption spectrum of 11-cis-retinal is strongly influenced by the presence of a cis bond between carbon atoms 11 and 12. The cis bond in this position results in two important spatial properties of the molecule: first, steric hindrance between the C13-methyl group and the C10-hydrogen atom; second, a bend in the system of conjugated double bonds. Both the steric hindrance and the bend in the molecule give rise to particular absorption bands. We now report the results of experiments which allow the identification of these absorption bands in the 11-cis-retinal spectrum.
TL;DR: In this paper, strong absorption lines due to free NS radicals have been observed by means of Stark modulated microwave spectrometers, in the discharge products of a mixture of nitrogen and sulfur dichloride or sulfur monochloride.
TL;DR: In this article, a new vacuum-uv absorption phenomena in helium are reported, and the most important of these consist of bands between 600 and 611 A. They are attributed to the transition A 1Σu+←X 1 Σg+ of He2.
Abstract: New vacuum‐uv absorption phenomena in helium are reported. The most important of these consist of bands between 600 and 611 A. Individual bands exhibit diffuse rotational structure and together form a υ′ progression. They are attributed to the transition A 1Σu+←X 1Σg+ of He2. Several rotational constants Bυ for the upper state are noted. The dissociation energy and the term value of the upper state are estimated. A minimum height for the potential “hump” in the upper state is determined to be 0.059 eV. The close connection between the emission and absorption bands of He2 around 600 A is indicated and discussed. The location of the He‐continuum (emission) peak is worked out in relation to the A‐state term value and the ground‐state potential function. A number of absorption bands were also observed in the range from 510–600 A. They are attributed to other singlet systems relating to ns and nd orbitals (n > 2).