Spectroscopy of the hydrogen molecular ion at its dissociation limit

1988 ◽  
Vol 324 (1578) ◽  
pp. 275-287 ◽  
Keyword(s):  
Ion Beam ◽  
Double Resonance ◽  
Spectroscopic Studies ◽  
Spin Rotation ◽  
Dissociation Limit ◽  
Hyperfine Constants ◽  
Vibrational Levels ◽  
Theoretical Predictions ◽  
Deuterium Isotopes ◽  
Vibration Rotation

Previous theoretical and experimental work on the ion and its deuterium isotopes HD+ and D£ is briefly reviewed. Spectroscopic studies of the vibration rotation levels are discussed, and recent work on the infrared photodissociation of the high-lying vibrational levels is described. Earlier work that made use of ion-beam techniques to study the vibration—rotation levels of HD+ is reviewed, and compared with the most recent theoretical predictions. The nuclear-hyperfine and spin—rotation structure of HD+ is described, and recent observations of the vibration-rotation satellite lines that will yield absolute values of the deuterium hyperfine constants are presented. We conclude by describing our attempts to observe radiofrequency—infrared double-resonance spectra.

Vibration-rotation bands of trideuteromethyl iodide

1965 ◽  
Vol 288 (1412) ◽  
pp. 39-49 ◽  
Keyword(s):  
Fine Structure ◽  
Coupling Constants ◽  
Coriolis Coupling ◽  
Molecular Constants ◽  
Rotational Constants ◽  
Vibrational Levels ◽  
Theoretical Predictions ◽  
Vibration Rotation ◽  
Combination Bands

The rotational fine structure of six parallel and nine perpendicular vibration bands of tri­deuteromethyl iodide has been analysed, and molecular constants have been derived. These include the band origins, the rotational constants in different vibrational levels, the α A i and α B i values, and the Coriolis coupling constants ς i for the fundamental degenerate vibrations. The ς values for overtone and combination bands have been compared with values calculated from the ς i values of the fundamentals, and agree closely with previous theoretical predictions.

The ultra-violet spectra of HF and DF

1959 ◽  
Vol 251 (1267) ◽  
pp. 504-518 ◽  
Keyword(s):  
Ground State ◽  
Ultra Violet ◽  
Electric Discharges ◽  
Excited Singlet ◽  
Potential Minimum ◽  
Large Numbers ◽  
Vibrational Levels ◽  
Theoretical Predictions ◽  
Vibration Rotation ◽  
Available Information

Successful analyses have been m ade of th e ultra-violet spectra excited by electric discharges in m ixtures of helium with HF or DF. The spectra, which consist of large numbers of irregularly spaced lines, are shown to arise from transitions V 1 Σ + - X 1 Σ + in neutral HF and DF. State X is the ground state: state V , the lowest stable excited singlet state, probably correlates with H + + F - . The potential minimum of state V lies at 10·5 eV above that of the ground state. The internuclear distance in this state —in agreement with theoretical predictions — is large, more than twice that in the ground state, so that the bands observed consist of transitions from low vibrational levels in V to high vibrational levels in X . In HF, the observed levels are 9 ≤ v " ≤ 19: predissociation by rotation is observed in the levels 10 ≤ v " ≤ 19. The last vibrational state which may have a few stable rotational levels is v " = 20, so that, by combining the present observations with those of the vibration-rotation bands, there is now available information about the vibrational and rotational levels over the greater part of their range of stable existence in the ground state. The dissociation energy, D" 0 , of HF is found to be 5·86 ±0·01 eV.

scholarly journals Excitation Spectrum of I2 Induced by Laser Radiation Near the Dissociation Limit of the B–State

1983 ◽  
Vol 1 (2) ◽  
pp. 83-112 ◽  
Author(s):  
Simon Gerstenkorn ◽  
Paul Luc
Keyword(s):  
Laser Radiation ◽  
Excitation Spectrum ◽  
Dissociation Limit ◽  
Molecular Constants ◽  
Vibrational Levels ◽  
Theoretical Predictions ◽  
X State ◽  
Good Agreement

The study of the excitation spectrum of I2 induced by laser radiation near the dissociation limit of the B state enables us to determine the molecular constants of the vibrational levels v′ = 78, 79 and 80; the latest being situated only 1.6 cm−1 from the dissociation limit. The molecular constants are now in good agreement with theoretical predictions. Revised values of the dissociation limits of the B and X state are proposed: they are 20043.176 ± 0.016 and 12440.200 ± 0.020 cm−1 respectively. The excitation spectrum from 20022 to 20039.5 cm−1 is entirely reproduced, together with the assignments and the wavenumbers of all observed lines, principally for calibration purposes.

The microwave spectrum of the OH X2Π radical in the ground and vibrationally-excited (ν ≤ 6) levels

1979 ◽  
Vol 57 (5) ◽  
pp. 619-634 ◽  
Author(s):  
J. A. Coxon ◽  
K. V. L. N. Sastry ◽  
J. A. Austin ◽  
D. H. Levy
Keyword(s):  
Absorption Spectrum ◽  
Parallel Plate ◽  
Microwave Spectrum ◽  
Hamiltonian Matrix ◽  
Centrifugal Distortion ◽  
Linear Least Squares ◽  
Vibrationally Excited ◽  
Hyperfine Constants ◽  
Vibrational Levels ◽  
Astrophysical Significance

The microwave absorption spectrum of the OH X2Π radical has been observed in all vibrational levels up to ν = 6. Experimental details are described of the tunable cavity and parallel plate Stark-modulated spectrometers employed for transitions below and above 23 GHz, respectively. The observed line frequencies, together with those reported by other workers, have been fitted using a non-linear least-squares routine with numerical diagonalization of the Hamiltonian matrix. Pseudo high-order corrections for centrifugal distortion of the Λ-doubling are required for the ν = 0 data, which now extend to J = 19/2 in the 2Π1/2 component. The various adjustable parameters of the Hamiltonian are compared with those of other similar models. The Λ-doubling and magnetic hyperfine constants for the different vibrational levels are reported, and several line frequencies of potential astrophysical significance are predicted.

Vibration-rotation bands and rotational constants of dideuteroacetylene

1955 ◽  
Vol 232 (1190) ◽  
pp. 291-309 ◽  
Keyword(s):  
Resolving Power ◽  
Vibrational States ◽  
Absorption Bands ◽  
Rotational Constants ◽  
Vibrational Assignments ◽  
Vibrational Anharmonicity ◽  
A Value ◽  
Vibrational Levels ◽  
Vibration Rotation ◽  
Very High

Nine vibrational absorption bands of dideutero-acetylene have been examined with very high resolving power. The rotational constants have been determined for the vibrational levels concerned, and the coefficients α i have been determined with more convincing accuracy than previously. In some of the bands the Q branches have been resolved, so that the l -doubling coefficients q i could be derived, and details could be established about the doublet components in some II levels. The results emphasize the need of high resolution if the vibrational assignments are to be unambiguous, and if reliable values of the rotational constants are to be derived. A value of B e has been obtained, and the vibrational anharmonicity coefficients have been considered briefly. Estimates of the centrifugal stretching constants D i in different vibrational states have been made, and one anomalous case has been found.

scholarly journals Electron nuclear double-resonance (ENDOR) spectroscopy of amine oxidase from pig plasma

1986 ◽  
Vol 237 (2) ◽  
pp. 609-612 ◽  
Author(s):  
G J Baker ◽  
P F Knowles ◽  
K B Pandeya ◽  
J B Rayner
Keyword(s):  
Hyperfine Coupling ◽  
Amine Oxidase ◽  
Double Resonance ◽  
Spectroscopic Studies ◽  
Water Molecules ◽  
Electron Nuclear Double Resonance ◽  
Endor Spectroscopy ◽  
Amino Acid Histidine ◽  
Plasma Amine Oxidase ◽  
Hyperfine Couplings

Electron nuclear double-resonance (‘ENDOR’) spectroscopic studies on pig plasma amine oxidase have been carried out at 15 K. Deuterium-exchange studies show the presence of two sets of exchangeable protons, probably from two water molecules; from the magnitude of their hyperfine couplings, one is assigned to be equatorially, and the other axially, co-ordinated. Only one 14N hyperfine coupling is observed, suggesting that the bonding of all amino acid (histidine) or organic cofactor ligands is similar. Upon addition of azide, a further hyperfine coupling to nitrogen is observed which is smaller than that observed for the native enzyme; the hyperfine couplings to the remaining nitrogens are slightly altered.

scholarly journals Comparison of HF and HCl Chemical Laser Parameters by using Mathematical Model

2007 ◽  
Vol 4 (1) ◽  
pp. 119-124
Author(s):  
Baghdad Science Journal
Keyword(s):  
Computer Program ◽  
Parametric Analysis ◽  
Rotational Constant ◽  
Published Data ◽  
Vibrational Quantum Number ◽  
Theoretical Comparison ◽  
Fabry Perot ◽  
Vibrational Levels ◽  
Hf Laser ◽  
Vibration Rotation

A simplified theoretical comparison of the hydrogen chloride (HCl) and hydrogen fluoride (HF) chemical lasers is presented by using computer program. The program is able to predict quantitative variations of the laser characteristics as a function of rotational and vibrational quantum number. Lasing is assumed to occur in a Fabry-Perot cavity on vibration-rotation transitions between two vibrational levels of hypothetical diatomic molecule. This study include a comprehensive parametric analysis that indicates that the large rotational constant of HF laser in comparison with HCl laser makes it relatively easy to satisfy the partial inversion criterion. The results of this computer program proved their credibility when compared with the little published data.

THE LYMAN BANDS OF MOLECULAR HYDROGEN

1959 ◽  
Vol 37 (5) ◽  
pp. 636-659 ◽  
Author(s):  
G. Herzberg ◽  
L. L. Howe
Keyword(s):  
High Resolution ◽  
Vibrational Level ◽  
Ground State ◽  
Molecular Hydrogen ◽  
Equilibrium Constants ◽  
Dissociation Limit ◽  
Vibrational Levels ◽  
State Formula ◽  
Single Formula ◽  
Vibrational Constants

The Lyman bands of H2 have been investigated under high resolution with a view to improving the rotational and vibrational constants of H2 in its ground state. Precise Bv and ΔG values have been obtained for all vibrational levels of the ground state. One or two of the highest rotational levels of the last vibrational level (v = 14) lie above the dissociation limit. Both the [Formula: see text] and ΔG″ curves have a point of inflection at about v″ = 3. This makes it difficult to represent the whole course of each of these curves by a single formula and therefore makes the resulting equilibrium constants somewhat uncertain. This uncertainty is not very great for the rotational constants for which we find[Formula: see text]but is considerable for the vibrational constants ωe and ωexe for which three-, four-, five-, and six-term formulae give results diverging by ± 1 cm−1. The rotational and vibrational constants for the upper state [Formula: see text] of the Lyman bands are also determined. An appreciable correction to the position of the upper state is found.

The high-resolution spectroscopy of dissociating molecules

1990 ◽  
Vol 332 (1625) ◽  
pp. 297-307 ◽  
Keyword(s):  
High Resolution ◽  
Energy Flow ◽  
Energy State ◽  
Reaction Dynamics ◽  
Theoretical Models ◽  
Spectroscopic Studies ◽  
High Resolution Spectroscopy ◽  
Bond Breaking ◽  
Vibrational Levels ◽  
Dynamical Constraints

Results from spectroscopic studies of the vibrational levels of dissociating molecules and from state-selected, state-resolved photofragmentation spectroscopy are presented. The extent of energy flow among the modes of a molecule is explored through the couplings, or lack thereof, revealed by high-resolution spectroscopy. The dynamics of energy flow during bond breaking are revealed by photofragment excitation spectroscopy and by product energy state distributions. These completely resolved data provide sensitive tests of dynamical constraints such as vibrational or rotational adiabaticity and thus of theoretical models for unimolecular reaction dynamics.

Ion Beam Synthesis of Luminescent SI and GE Nanocrystals in a Silicon Dioxide Matrix

1993 ◽  
Vol 316 ◽  
Author(s):  
H.A. Atwater ◽  
K.V. Shcheglov ◽  
S.S. Wong ◽  
K.J. Vahala ◽  
R.C. Flagan ◽  
...  
Keyword(s):  
Ion Beam ◽  
Optoelectronic Device ◽  
Structural Defects ◽  
Si Substrates ◽  
Localized State ◽  
Transmission Electron ◽  
Ion Beam Synthesis ◽  
Theoretical Predictions ◽  
Device Applications ◽  
Ge Nanocrystals

ABSTRACTIon beam synthesis of Si and Ge nanocrystals in an SiO2 matrix is performed by precipitation from supersaturated solid solutions created by ion implantation. Films of SiO2 on (100) Si substrates are implanted with Si and Ge at doses 1 × 1016/cm2 - 5 × 1016/cm2. Implanted samples are subsequently annealed to induce precipitation of Si and Ge nanocrystals. Raman spectroscopy and high-resolution transmission electron microscopy indicate a correlation between visible room-temperature photoluminescence and the formation of diamond cubic nanocrystals approximately 2–5 nm in diameter in annealed samples. As-implanted but unannealed samples do not exhibit luminescence. Rutherford backscattering spectra indicate a steepening of implanted Ge profiles upon annealing. Photoluminescence spectra are correlated with annealing temperatures, and compared with theoretical predictions for various possible luminescence mechanisms, such as radiative recombination of quantum-confined excitons, as well as possible localized state luminescence related to structural defects in SiO2. Potential optoelectronic device applications are also discussed.

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