scholarly journals Effective Excitation of High Vibrational States of SF6 Molecules in a Beam by a Multiple-frequency IR Radiation

1985 ◽  
Vol 5 (4) ◽  
pp. 231-237 ◽  
Author(s):  
Valentin M. Apatin ◽  
Valerii N. Lokhman ◽  
Grigorii N. Makarov
Keyword(s):  
Absorption Spectrum ◽  
Multiple Frequency ◽  
Effective Population ◽  
Vibrational States ◽  
Ir Radiation ◽  
Linear Absorption ◽  
Photon Excitation ◽  
First Results ◽  
Excited Molecules ◽  
Effective Excitation

Presented here are the first results of experiments on multiple-photon excitation (MPE) of molecules upon their being concurrently irradiated by several IR pulses differing in frequency. Effective population of the high vibrational states (HVS) of SF6 was found to occur even when the frequencies of exciting pulses were fairly far (10–20 cm–1) from the linear absorption spectrum (LAS) of the molecules. The method enables one to obtain narrow vibrational distributions of excited molecules (VDEM) and make a wider use of the capabilities of IR lasers for selective photochemistry purposes.

scholarly journals Evidence of a significant rotational non-LTE effect in the CO<sub>2</sub> 4.3 µm PFS-MEX limb spectra

2017 ◽  
Vol 10 (1) ◽  
pp. 265-271 ◽  
Author(s):  
Alexander A. Kutepov ◽  
Ladislav Rezac ◽  
Artem G. Feofilov
Keyword(s):  
Near Infrared ◽  
Thermal Structure ◽  
Radiative Lifetime ◽  
Martian Atmosphere ◽  
Vibrational States ◽  
Rotational States ◽  
First Results ◽  
Rotational Distribution ◽  
Multi Level ◽  
Excited Molecules

Abstract. Since January 2004, the planetary Fourier spectrometer (PFS) on board the Mars Express satellite has been recording near-infrared limb spectra of high quality up to the tangent altitudes ≈ 150 km, with potential information on density and thermal structure of the upper Martian atmosphere. We present first results of our modeling of the PFS short wavelength channel (SWC) daytime limb spectra for the altitude region above 90 km. We applied a ro-vibrational non-LTE model based on the stellar astrophysics technique of accelerated lambda iteration (ALI) to solve the multi-species and multi-level CO2 problem in the Martian atmosphere. We show that the long-standing discrepancy between observed and calculated spectra in the cores and wings of 4.3 µm region is explained by the non-thermal rotational distribution of molecules in the upper vibrational states 10011 and 10012 of the CO2 main isotope second hot (SH) bands above 90 km altitude. The redistribution of SH band intensities from band branch cores into their wings is caused (a) by intensive production of the CO2 molecules in rotational states with j > 30 due to the absorption of solar radiation in optically thin wings of 2.7 µm bands and (b) by a short radiative lifetime of excited molecules, which is insufficient at altitudes above 90 km for collisions to maintain rotation of excited molecules thermalized. Implications for developing operational algorithms for massive processing of PFS and other instrument limb observations are discussed.

scholarly journals Evidence of a significant rotational non-LTE effect in the CO<sub>2</sub> 4.3 μm PFS-MEX limb spectra

2016 ◽  
Author(s):  
Alexander A. Kutepov ◽  
Ladislav Rezac ◽  
Artem G. Feofilov
Keyword(s):  
Near Infrared ◽  
Thermal Structure ◽  
Life Time ◽  
Martian Atmosphere ◽  
Vibrational States ◽  
Rotational States ◽  
First Results ◽  
Rotational Distribution ◽  
Multi Level ◽  
Excited Molecules

Abstract. Since January 2004, the planetary Fourier spectrometer (PFS) on board the Mars Express satellite has been recording near infrared limb spectra of high quality up to &amp;approx; 150 km, with potential information on density and thermal structure of the upper atmosphere. We present first results of our modeling of the PFS short wavelength channel (SWC) daytime limb spectra for the altitude region above 90 km. We applied a ro-vibrational non-LTE model based on the stellar astrophysics technique of accelerated lambda 5 iteration (ALI) to solve the multi-species and multi-level CO2 problem in the Martian atmosphere. We show that the long standing discrepancy between observed and calculated spectra in the cores and wings of 4.3 μm region is explained by the non-thermal rotational distribution of molecules in the upper vibrational states 10011 and 10012 of the CO2 main isotope second hot (SH) bands above 90 km altitude. The redistribution of SH band intensities from band branch cores into their wings is caused (a) by intensive production of the CO2 molecules in rotational states with j > 30 due to the absorption 10 of solar radiation in optically thin wings of 2.7 μm bands, and (b) by a short radiative life time of excited molecules, which is insufficient at altitudes above 90 km for collisions to maintain rotation of excited molecules thermalized. Implications for developing operational algorithms for massive processing of PFS and other instrument limb observations are discussed.

Interaction Potentials of Hg-Ar from Temperature Dependent Absorption Spectra

1978 ◽  
Vol 33 (12) ◽  
pp. 1461-1468 ◽  
Author(s):  
H. C. Petzold ◽  
W. Behmenburg
Keyword(s):  
Absorption Spectrum ◽  
Thermal Energy ◽  
Short Wavelength ◽  
Line Broadening ◽  
Vibrational States ◽  
Temperature Dependent ◽  
Satellite Structure ◽  
Lennard Jones ◽  
Dependent Absorption ◽  
Short Wavelength Side

Abstract The temperature dependence of the absorption spectrum k(v̄) of Hg-Ar-mixtures in the range 30-1000 cm-1 about the center of the Hg-line at v̄0 = 39425 cm-1 (λ0 = 2536.5 Å) has been investigated in the temperature interval 473 -1273 K. The measurements were carried out at number densities 1.0 x 1017-9.1 X 1018 cm-3 for Hg and 9.4 x 1018-9.7 x 1018 cm-3 for Ar. Potentials for the Hg-Ar-system in the thermal energy range originating from the Hg-states 61S0 and 63P1 have been deduced from the data. It turned out that they differ considerably from Lennard-Jones-functions. By comparison of the observed spectra with calculations on the basis of quantummechanical theory of collisional line broadening it is concluded that transitions from free translational states of Hg-Ar-pairs as well as bound and quasi-bound vibrational states of the Hg-Ar-molecule contribute to the formation of the satellite structure on the short wavelength side of the Hg-line.

Multiple photon excitation of polyatomic molecules from the many rotational states by an intense pulse of IR radiation

1977 ◽  
Vol 23 (3) ◽  
pp. 357-361 ◽  
Author(s):  
A.S. Akhmanov ◽  
V.Yu. Baranov ◽  
V.D. Pismenny ◽  
V.N. Bagratashvili ◽  
Yu.R. Kolomiisky ◽  
...  
Keyword(s):  
Polyatomic Molecules ◽  
Ir Radiation ◽  
Rotational States ◽  
Photon Excitation ◽  
The Many

scholarly journals Расчет колебательных параметров молекулы с электридными свойствами Li-=SUB=-4-=/SUB=-C-=SUB=-4-=/SUB=-H-=SUB=-2-=/SUB=-N-=SUB=-2-=/SUB=- и молекулы пиридазина C-=SUB=-4-=/SUB=-H-=SUB=-4-=/SUB=-N-=SUB=-2-=/SUB=-

2019 ◽  
Vol 127 (8) ◽  
pp. 218
Author(s):  
В.П. Булычев ◽  
М.В. Бутурлимова
Keyword(s):  
Absorption Spectrum ◽  
Spectroscopic Observation ◽  
Atomic Function ◽  
Hydrogen Atoms ◽  
Vibrational States ◽  
Spectral Parameters

The frequencies and intensities for fundamental transitions between vibrational states of an electride-like molecule Li4C4H2N2 that can be obtained from the pyridazine molecule C4H4N2 by substituting lithium atoms for two hydrogen atoms and adding two other lithium atoms to nitrogen atoms are calculated. Spectral parameters of Li4C4H2N2 are calculated in the harmonic and anharmonic approximations using the MP2, CCSD, and QCISD methods with the atomic function sets aug-cc-pVDZ and aug-cc-pVTZ. For comparison the absorption spectrum of a pyridazine molecule was calculated in the same approximations. The calculations showed that new intense bands appear upon entering lithium atoms into the pyridazine molecule and the spectral parameters of bands present in the pyridazine spectrum are significantly changed. The results obtained may be useful for spectroscopic observation and identification of the new compound.

Synthesis, characterization, and femtosecond third-order optical nonlinearity of Au@Ag core–shell nanoparticles

2021 ◽  
Author(s):  
Heng Lu ◽  
Bing Gu
Keyword(s):  
Absorption Spectrum ◽  
Photoelectron Spectroscopy ◽  
Nonlinear Refraction ◽  
Optical Nonlinearity ◽  
Core Shell ◽  
Third Order ◽  
Shell Nanoparticles ◽  
Linear Absorption ◽  
X Ray ◽  
Core Shell Nanoparticles

In this work, the Au@Ag bimetallic core–shell nanostructures were synthesized by a seed-mediated growth. The crystal structure, morphology, elemental composition, atomic concentration, and absorption spectrum of the as-synthesized nanoparticles were characterized by means of X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet–visible linear absorption spectrum, respectively. The femtosecond third-order optical nonlinearities of nanoparticle dispersions were investigated by carrying out the femtosecond-pulsed [Formula: see text]-scan measurements at 800[Formula: see text]nm. The experimental results indicate that Au@Ag core–shell nanoparticles exhibit the positive refractive nonlinearity and negative absorptive nonlinearity. The third-order nonlinear refraction indexes of Au and Au@Ag nanoparticles are measured to be [Formula: see text] and [Formula: see text][Formula: see text]cm2/GW, respectively. The results show that the bimetallic nanoparticle has potential possibility in nonlinear photonic applications.

scholarly journals The theory of the continuous absorption spectrum of bromine

1937 ◽  
Vol 158 (895) ◽  
pp. 551-561 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Wave Number ◽  
Electronic Transitions ◽  
Complex Nature ◽  
Frequency Range ◽  
Vibrational States ◽  
Energy Functions ◽  
Potential Energy Functions ◽  
Continuous Absorption ◽  
The Continuum

The discovery of the complex nature of the visible continuous absorption spectrum of bromine by Acton, Aickin, and Bayliss made it interesting to investigate the continuum theoretically, since the interpretation of the two components that they found to be present is still uncertain. The investigation also provides another application of the potential energy functions and eigenfunctions that were used by Gibson, Rice, and Bayliss in their treatment of the continuous absorption spectrum of chlorine, although the theory has been slightly modified. The experimental data with which the theory is to be compared consist of values at a number of wave-lengths of ε 0 and ε 1 , the absorption coefficients appropriate to the vibrational states v ″ = 0 and 1 respectively, which were determined by an analysis of the temperature variation of the observed absorption coefficient ε. For bromine, the curve of ε 0 against wave number was shown to consist of the sum of the ε 0 curves of two overlapping continua, which arise from separate electronic transitions from the ground state ( 1 ∑ g + ), and which were temporarily designated as A ( λ max . = 4150 A.) and B ( λ max . = 4950 A.). Dirac has shown that the probability per second of the absorption of radiation by an atom from a beam of photons whose intensity is one photon/unit frequency range/cm. 2 /second is k = (8π 3 v /3 hc ) | ( α ′ | D | α ″) | 2 .

Sign in / Sign up

Export Citation Format

Share Document