Gas phase photoacoustic Raman spectroscopy using pulsed laser excitation

1980 ◽  
Vol 51 (5) ◽  
pp. 2823 ◽  
Author(s):  
Gary A. West ◽  
Donald R. Siebert ◽  
Joseph J. Barrett
Keyword(s):  
Raman Spectroscopy ◽  
Gas Phase ◽  
Laser Excitation ◽  
Pulsed Laser

scholarly journals Reactive quenching of electronically excited NO<sub>2</sub><sup>∗</sup> and NO<sub>3</sub><sup>∗</sup> by H<sub>2</sub>O as potential sources of atmospheric HO<sub><i>x</i></sub> radicals

2018 ◽  
Vol 18 (19) ◽  
pp. 14005-14015 ◽  
Author(s):  
Terry J. Dillon ◽  
John N. Crowley
Keyword(s):  
Gas Phase ◽  
Laser Excitation ◽  
Pulsed Laser ◽  
Work Rate ◽  
Rate Coefficients ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Upper Limit ◽  
Upper Limits ◽  
Electronically Excited

Abstract. Pulsed laser excitation of NO2 (532–647 nm) or NO3 (623–662 nm) in the presence of H2O was used to initiate the gas-phase reaction NO2∗+H2O → products (Reaction R5) and NO3∗+H2O → products (Reaction R12). No evidence for OH production in Reactions (R5) or (R12) was observed and upper limits for OH production of k5b/k5<1×10-5 and k12b/k12<0.03 were assigned. The upper limit for k5b∕k5 renders this reaction insignificant as a source of OH in the atmosphere and extends the studies (Crowley and Carl, 1997; Carr et al., 2009; Amedro et al., 2011) which demonstrate that the previously reported large OH yield by Li et al. (2008) was erroneous. The upper limit obtained for k12b∕k12 indicates that non-reactive energy transfer is the dominant mechanism for Reaction (R12), though generation of small but significant amounts of atmospheric HOx and HONO cannot be ruled out. In the course of this work, rate coefficients for overall removal of NO3∗ by N2 (Reaction R10) and by H2O (Reaction R12) were determined: k10=(2.1±0.1)×10-11 cm3 molecule−1 s−1 and k12=(1.6±0.3)×10-10 cm3 molecule−1 s−1. Our value of k12 is more than a factor of 4 smaller than the single previously reported value.

scholarly journals Reactive quenching of electronically excited NO<sub>2</sub><sup>*</sup> and NO<sub>3</sub><sup>*</sup> by H<sub>2</sub>O as potential sources of atmospheric HO<sub><i>x</i></sub> radical

2018 ◽  
Author(s):  
Terry J. Dillon ◽  
John N. Crowley
Keyword(s):  
Gas Phase ◽  
Laser Excitation ◽  
Pulsed Laser ◽  
Gas Phase Reactions ◽  
Upper Limits ◽  
Potential Sources ◽  
Electronically Excited

Abstract. Pulsed laser excitation of NO2 (532–647 nm) or NO3 (623–662 nm) in the presence of H2O was used to initiate the gas-phase reactions NO2* + H2O → products (R5) and NO3* + H2O → products (R12). No evidence for OH production in (R5) or (R12) was observed and upper-limits for OH production of k5b/k5 

Suppression of Luminescence Background in Raman Spectroscopy by Means of Transient Optical Depletion of Causal Impurity Molecules

1987 ◽  
Vol 41 (8) ◽  
pp. 1265-1268 ◽  
Author(s):  
H. Hamaguchi ◽  
T. Tahara ◽  
M. Tasumi
Keyword(s):  
Raman Spectroscopy ◽  
Model Calculation ◽  
Efficient Method ◽  
Biological Samples ◽  
Laser Excitation ◽  
Pulsed Laser ◽  
Luminescence Quenching ◽  
Highly Efficient ◽  
Quenching Efficiency ◽  
Adenine Thymine

A simple but highly efficient method of luminescence quenching in Raman spectroscopy is proposed—made on the basis of a newly recognized phenomenon which is ascribable to the optical depletion of luminescent impurity molecules by pulsed-laser excitation. The method has been applied to two typical biological samples: a DNA tetramer (AATT; adenine-adenine-thymine-thymine) and a protein (calmodulin). Suppression of luminescence background by factors of 10–100 was achieved by changing the mode of excitation from cw to pulsed. A model calculation based on semiquantitative estimation of photoexcitation rates successfully accounts for the observed quenching efficiency.

scholarly journals Raman spectroscopy of graphene under ultrafast laser excitation

2019 ◽  
Vol 205 ◽  
pp. 05003
Author(s):  
Carino Ferrante ◽  
Alessandra Virga ◽  
Lara Benfatto ◽  
Miles Martinati ◽  
Domenico De Fazio ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Phonon Spectrum ◽  
Laser Excitation ◽  
Pulsed Laser ◽  
Ultrafast Laser ◽  
Dirac Cone ◽  
Raman Response

The out-of-equilibrium Raman response of graphene is addressed by pulsed laser excitation. Phonon spectrum is rationalized by revisiting the electron-phonon picture in the light of a transient broadening of the Dirac cone.

Crystallization of Molybdenum Disulfide Films Deposited by Pulsed Laser Ablation

1990 ◽  
Vol 201 ◽  
Author(s):  
J. S. Zabinski ◽  
M. S. Donley ◽  
P. J. John ◽  
V. J. Dyhouse ◽  
A. J. Safriet ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Raman Spectroscopy ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Emerging Technology ◽  
Substrate Material ◽  
Post Deposition Annealing ◽  
Film Properties ◽  
Deposition Parameters ◽  
Post Deposition

AbstractPulsed laser ablation (PLA) is an emerging technology that provides a mechanism to deposit lubricious films and to tailor film properties by the appropriate choice of substrate materials, deposition parameters and post deposition treatments. The properties of MoS2 films deposited by PLA are evaluated as a function of: (1) substrate material, (2) duration of post deposition annealing treatments using 248 nm laser radiation and (3) substrate temperature during deposition. The chemistry and crystal structure of the different films are determined using small angle X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). The tribological properties of the films are then evaluated as a function of their chemistry and crystal structure.

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