scholarly journals Stimulated-Emission-Pumping Laser-Induced-Fluorescence Spectroscopy of Phenol and Anisole

1994 ◽  
Vol 14 (1-3) ◽  
pp. 103-117 ◽  
Author(s):  
Masao Takayanagi ◽  
Ichiro Hanazaki
Keyword(s):  
Vibrational Relaxation ◽  
Dynamical Behavior ◽  
Low Frequency ◽  
Laser Induced Fluorescence ◽  
Stimulated Emission ◽  
Torsional Motion ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Supersonic Expansion ◽  
Methyl Group

The SEP–LIF (stimulated emission pumping-laser induced fluorescence) technique was applied to the investigation of dynamical behavior of vibrationally excited phenol and anisole produced in the supersonic expansion. In the SEP–LIF scheme, a molecule excited to a specific vibrational state by SEP is detected by measuring the LIF excitation spectrum with an appropriate delay to probe the vibrational relaxation. Four vibrational states, 6a1, 16a2, 121 and 11, of phenol, and six vibrational states, 18b1, 18b2, 6a1, 121, 16a2 and 11, of anisole were investigated. For both of phenol and anisole, it is found that the relaxation of the vibrational states below 1,000 cm-1 in the ground electronic state is so slow under the collisionless condition that only the transitions from the vibrational states initially prepared by SEP are observed as the SEP-induced bands in the SEP–LIF spectra. The low frequency torsional motion of methyl group in anisole does not accelerate IVR (intramolecular vibrational redistribution) much in this energy region.

scholarly journals Observation of Intermode Coupling in the 3μm IR Multiple Photon Excitation of Propylene

1983 ◽  
Vol 1 (5) ◽  
pp. 177-183 ◽  
Author(s):  
R. L. Woodin ◽  
C. F. Meyer
Keyword(s):  
Energy Deposition ◽  
Excited Molecule ◽  
Vibrational Modes ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Laser Chemistry ◽  
Methyl Group ◽  
Photon Excitation ◽  
Deuterium Substitution

The mechanism of IR multiple photon excitation through the dense manifold of vibrational states, usually called the quasicontinuum, of a vibrationally excited molecule is one of the unresolved issues in the field of laser chemistry. The effects of deuterium substitution on propylene IR multiple photon excitation are used to identify the vibrational modes leading to efficient excitation. Optoacoustic energy deposition data show that for propylene, 3 μm multiple photon excitation occurs most efficiently at the methyl group, and furthermore that efficient methyl group excitation requires the CH group on the adjacent carbon. Thus 3 μm multiple photon excitation of propylene, while involving energy deposition directly into several spatially discrete intramolecular groups, is found to be enhanced by specific intramolecular couplings. Implications of this result for mechanisms of IR multiple photon excitation are discussed.

scholarly journals Progresses on the Use of Two-Photon Absorption Laser Induced Fluorescence (TALIF) Diagnostics for Measuring Absolute Atomic Densities in Plasmas and Flames

Plasma ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 145-171
Author(s):  
Kristaq Gazeli ◽  
Guillaume Lombardi ◽  
Xavier Aubert ◽  
Corinne Y. Duluard ◽  
Swaminathan Prasanna ◽  
...  
Keyword(s):  
Optical Transition ◽  
Thin Film Deposition ◽  
Laser Induced Fluorescence ◽  
Film Deposition ◽  
Stimulated Emission ◽  
Photon Absorption ◽  
Collisional Quenching ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Wide Range

Recent developments in plasma science and technology have opened new areas of research both for fundamental purposes (e.g., description of key physical phenomena involved in laboratory plasmas) and novel applications (material synthesis, microelectronics, thin film deposition, biomedicine, environment, flow control, to name a few). With the increasing availability of advanced optical diagnostics (fast framing imaging, gas flow visualization, emission/absorption spectroscopy, etc.), a better understanding of the physicochemical processes taking place in different electrical discharges has been achieved. In this direction, the implementation of fast (ns) and ultrafast (ps and fs) lasers has been essential for the precise determination of the electron density and temperature, the axial and radial gradients of electric fields, the gas temperature, and the absolute density of ground-state reactive atoms and molecules in non-equilibrium plasmas. For those species, the use of laser-based spectroscopy has led to their in situ quantification with high temporal and spatial resolution, with excellent sensitivity. The present review is dedicated to the advances of two-photon absorption laser induced fluorescence (TALIF) techniques for the measurement of reactive species densities (particularly atoms such as N, H and O) in a wide range of pressures in plasmas and flames. The requirements for the appropriate implementation of TALIF techniques as well as their fundamental principles are presented based on representative published works. The limitations on the density determination imposed by different factors are also discussed. These may refer to the increasing pressure of the probed medium (leading to a significant collisional quenching of excited states), and other issues originating in the high instantaneous power density of the lasers used (such as photodissociation, amplified stimulated emission, and photoionization, resulting to the saturation of the optical transition of interest).

Laser induced fluorescence and vibrational relaxation in CO+

1977 ◽  
Vol 50 (2) ◽  
pp. 275-277 ◽  
Author(s):  
Terry A. Miller ◽  
V.E. Bondybey
Keyword(s):  
Vibrational Relaxation ◽  
Laser Induced Fluorescence

Contribution of the Torsional Modes to the Equilibrium Distribution of Vibrational States and to the Specific Heat of a Chain Molecule

1983 ◽  
Vol 38 (12) ◽  
pp. 1285-1292 ◽  
Author(s):  
J. A. Borges da Costa ◽  
C. Scherer ◽  
A. Holz ◽  
J. Naghizadeh
Keyword(s):  
Specific Heat ◽  
Equilibrium Distribution ◽  
Spatial Configuration ◽  
Low Frequency ◽  
Chain Molecule ◽  
Vibrational States ◽  
Polymer Molecules ◽  
The Mean ◽  
A Chain ◽  
Increasing Temperature

Abstract The torsional modes of a chain molecule were studied recently under the assumption that it has a well defined spatial configuration at any time. Here we show how the averages over the possible configurations, for a distribution in thermal equilibrium, should be performed in the calculation of the thermodynamical properties. Our results show that the mean density of torsional states increases in the low frequency region with increasing temperature. The specific heat behaviour shows a considerable difference from the result obtained in the previous paper, where only the lowest energetic configuration was considered. The consequences of this result with respect to the configurational properties of polymer molecules near the θ temperature are discussed.

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