scholarly journals The Schumann-Runge O2 Emission, Following Visible Multiphoton Excitation of NO2

1983 ◽  
Vol 1 (2) ◽  
pp. 113-130 ◽  
Author(s):  
Y. Matsumi ◽  
Y. Murasawa ◽  
K. Obi ◽  
I. Tanaka
Keyword(s):  
Excited State ◽  
Excitation Spectrum ◽  
Wavelength Range ◽  
Vibrational Relaxation ◽  
Multiphoton Excitation ◽  
Vibrationally Excited ◽  
Multiphoton Process ◽  
Vibrational Levels ◽  
Visible Laser ◽  
X State

The Schumann-Runge emission (B3Σu− − X3Σg−) of oxygen was observed in the wavelength range of 220–300 nm, when NO2 was irradiated with a focused visible laser (470–580 nm). The excitation spectrum of the emission also showed the Schumann-Runge transition from highly excited vibrational levels (v″ = 22–26) of the X state to the v′ = 1–3 levels of the B state of oxygen. The highly vibrationally excited O2 (Evib ≃ 30000 cm−1) is once produced through a multiphoton process of NO2 and then absorbs one more photon. The resulting excited state of O2 emits fluorescence in the UV region. Even at 40 torr of NO2, no rotational-vibrational relaxation in the B state was observed. The mechanism of the multiphoton process is discussed.

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.

Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

2019 ◽  
Author(s):  
Matthew M. Brister ◽  
Carlos Crespo-Hernández
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Transient Absorption ◽  
Electronic Energy ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Vibrationally Excited ◽  
Excited State Dynamics ◽  
Π State

<p></p><p> Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived <sup>1</sup>n<sub>O</sub>π* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived <sup>3</sup>ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.</p><p></p>

Molecules in strong laser fields: vibrational inversion and harmonic generation

1994 ◽  
Vol 72 (3) ◽  
pp. 673-677 ◽  
Author(s):  
Eric E. Aubanel ◽  
André D. Bandrauk
Keyword(s):  
Harmonic Generation ◽  
Laser Pulses ◽  
Harmonic Spectrum ◽  
Femtosecond Laser Pulses ◽  
Generation Process ◽  
High Order Harmonic Generation ◽  
Vibrationally Excited ◽  
Potential Wells ◽  
High Order Harmonic ◽  
Vibrational Levels

We examine two consequences of the unique behaviour of molecules in strong fields. First, by time gating of laser-induced avoided crossings with femtosecond laser pulses, one can obtain efficient vibrational inversion into a narrow distribution of vibrational levels of a molecular ion. We demonstrate this by numerical solution of the time-dependent Schrödinger equation for [Formula: see text] Second, we show results of numerical calculation with vibrationally excited [Formula: see text] of harmonic generation up to the 11th order of an intense 1064- nm laser. We predict that competition of photodissociation can be minimized by trapping the molecule in high-field-induced potential wells, thus enhancing the high-order harmonic generation process. Furthermore, the harmonic spectrum can serve as a measure of the structure of these laser-induced potentials.

Altitude dependence of the vibrational distribution of in the nightglow and the possible effects of vibrational excitation in the formation of O(1S)

1984 ◽  
Vol 62 (8) ◽  
pp. 780-788 ◽  
Author(s):  
I. C. McDade ◽  
E. J. Llewellyn ◽  
R. G. H. Greer ◽  
G. Witt
Keyword(s):  
Vibrational Relaxation ◽  
Vibrational Excitation ◽  
Relaxation Model ◽  
Terrestrial Atmosphere ◽  
Transfer Step ◽  
Vibrational Distribution ◽  
Altitude Dependence ◽  
Vibrational Levels ◽  
The Individual

A simple vibrational relaxation model that reproduces the observed vibrational distribution of the [Formula: see text] Herzberg II bands in the terrestrial nightglow is used to derive the altitude profiles of the fractional populations in the individual vibrational levels. Through consideration of these profiles it is shown that if [Formula: see text] is the Barth precursor of O(1S) in the nightglow then, at least in the terrestrial atmosphere, the higher vibrational levels appear to be more effective in the Barth transfer step than the lower vibrational levels.

ChemInform Abstract: EXCITED-STATE INTRAMOLECULAR PROTON TRANSFER AND VIBRATIONAL RELAXATION IN 2-(2-HYDROXYPHENYL)BENZOTHIAZOLE

1983 ◽  
Vol 14 (28) ◽  
Author(s):  
K. DING ◽  
S. J. COURTNEY ◽  
A. J. G. STRANDJORD ◽  
S. FLOM ◽  
D. M. FRIEDRICH ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Vibrational Relaxation ◽  
Intramolecular Proton Transfer

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.

scholarly journals Decay Rate Measurement of the First Vibrationally Excited State ofMgH+in a Cryogenic Paul Trap

2013 ◽  
Vol 111 (5) ◽  
Author(s):  
O. O. Versolato ◽  
M. Schwarz ◽  
A. K. Hansen ◽  
A. D. Gingell ◽  
A. Windberger ◽  
...  
Keyword(s):  
Excited State ◽  
Decay Rate ◽  
Paul Trap ◽  
Rate Measurement ◽  
Vibrationally Excited

scholarly journals Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

1997 ◽  
Vol 15 (8) ◽  
pp. 984-998 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Electron Density ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Atomic Oxygen ◽  
Major Ions ◽  
Integral Intensity ◽  
Rate Coefficients ◽  
Vibrationally Excited ◽  
Vibrational Distribution ◽  
Vibrational Levels

Abstract. This study compares the OV1-10 satellite measurements of the integral airglow intensities at 630 nm in the SAR arc regions observed in the northern and southern hemisphere as a conjugate phenomenon, with the model results obtained using the time-dependent one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the IZMIRAN model) during the geomagnetic storm of the period 15–17 February 1967. The major enhancements to the IZMIRAN model developed in this study are the inclusion of He+ ions (three major ions: O+, H+, and He+, and three ion temperatures), the updated photochemistry and energy balance equations for ions and electrons, the diffusion of NO+ and O2+ ions and O(1D) and the revised electron cooling rates arising from their collisions with unexcited N2, O2 molecules and N2 molecules at the first vibrational level. The updated model includes the option to use the models of the Boltzmann or non-Boltzmann distributions of vibrationally excited molecular nitrogen. Deviations from the Boltzmann distribution for the first five vibrational levels of N2 were calculated. The calculated distribution is highly non-Boltzmann at vibrational levels v > 2 and leads to a decrease in the calculated electron density and integral intensity at 630 nm in the northern and southern hemispheres in comparison with the electron density and integral intensity calculated using the Boltzmann vibrational distribution of N2. It is found that the intensity at 630 nm is very sensitive to the oxygen number densities. Good agreement between the modelled and measured intensities is obtained provided that at all altitudes of the southern hemisphere a reduction of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the IZMIRAN model with the non-Boltzmann vibrational distribution of N2. The effect of using of the O(1D) diffusion results in the decrease of 4–6% in the calculated integral intensity of the northern hemisphere and 7–13% in the calculated integral intensity of the southern hemisphere. It is found that the modelled intensities of the southern hemisphere are more sensitive to the assumed values of the rate coefficients of O+(4S) ions with the vibrationally excited nitrogen molecules and quenching of O+(2D) by atomic oxygen than the modelled intensities of the northern hemisphere.

Microwave Spectrum and Nuclear Quadrupole Coupling of 2-Chloropyridine

1987 ◽  
Vol 42 (2) ◽  
pp. 197-206 ◽  
Author(s):  
M. Meyer ◽  
U. Andresen ◽  
H. Dreizler
Keyword(s):  
Excited State ◽  
Ground State ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Vibrationally Excited ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Mo Theory

The microwave spectrum of 2-chloropyridine, 2-Cl(C5H4N), has been studied to determine the 35Cl, 37Cl and 14N nuclear quadrupole coupling constants. The results are discussed within a simple MO theory. We propose an approximate r0-structure under certain assumptions. In addition to the ground state we observed one vibrationally excited state of both chlorine isotopic species of 2-chloropyridine.

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