Electronic Energy Distribution in SrF by Investigation of the Molecular Chemiluminescence SrF(A2II1/2,3,2B2Σ+ → X2Σ+) and the Atomic Resonance Fluorescence Sr(53P1-51S0) in the Time-Domain following the Pulsed Dye Laser Generation of Sr(53PJ) in the prese

1995 ◽  
Vol 99 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Stephen Antrobus ◽  
Shaun A. Carl ◽  
David Husain ◽  
Jie Lei ◽  
Fernando Castaño ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Time Domain ◽  
Electronic Energy ◽  
Dye Laser ◽  
Pulsed Dye Laser ◽  
Laser Generation ◽  
Resonance Fluorescence ◽  
Atomic Resonance ◽  
The Time Domain

scholarly journals Time-Resolved Investigation of the Molecular Chemiluminescence SrI(A2∏1/2,3,2,B2∑+→X2∑+) and the Atomic Resonance Fluorescence Sr(53P1→51S0) Following The Pulsed Dye Laser Generation Of Sr(53PJ) in the Presence of CF3I

1995 ◽  
Vol 16 (2) ◽  
pp. 121-138 ◽  
Author(s):  
S. Antrobus ◽  
D. Husain ◽  
Jie Lei ◽  
F. Castaño ◽  
M. N. Sanchez Rayo
Keyword(s):  
Ground State ◽  
Branching Ratio ◽  
Atomic Emission ◽  
Electronic Energy ◽  
Dye Laser ◽  
Pulsed Dye Laser ◽  
Laser Generation ◽  
Buffer Gas ◽  
Resonance Fluorescence ◽  
Time Resolved

A time-resolved investigation is presented of the electronic energy distribution in SrI following the collision of the optically metastable strontium atom, Sr [5s5p(3PJ)], with the molecule CF3I. Sr[5s5p(3PJ)], 1.807 eV above its 5s2(1S0) electronic ground state, was generated by pulsed dye-laser excitation of ground state strontium vapour to the Sr(53P1) state at , λ =689.3 nm {Sr(53P1←51S0)} at elevated temperature (840 K) in the presence of excess helium buffer gas in which rapid Boltzmann equilibration within the 53PJ spin-orbit manifold takes place. Time resolved atomic emission from Sr(53P1→51S0) at the resonance transition and the molecular chemiluminescence from SrI(A2∏1,2,3/2,B2∑+→X2∑+) resulting from reaction of the excited atom with CF3I were recorded and shown to be exponential in character. SrI in the A2∏1/2,3/2 (172.5, 175.4 kJ mol-1) and B2∑+ (177.3 kJ mol-1) states are energetically accessible on collision by direct-I-atomic abstraction between Sr(3P) and CF3I. The first-order decay coefficients for the atomic and molecular emissions are found to be equal under identical conditions and hence SrI(A2∏1/2,3/2, B2∑+) are shown to arise from direct I- atom abstraction reactions. The molecular systems recorded were SrI (A2∏1/2→X2∑+, Δv=0, λ=694 nm), SrI(A2∏3/2→X2∑+, Δv=0, λ=677 nm) and SrI(B2∑+→X2∑+) (Δv=0, λ=674 nm), dominated by the Δv=0 sequences on account of Franck-Condon considerations. The combination of integrated m61ecular and atomic intensity measurements yields estimates of the branching ratios into the specific electronic states, A1/2, A3/2 and B, arising from Sr(53PJ)+CF3I which are found to be as follows: A1/2,1.2 × 10-2; A3/2, 6.7 × 10-3; B, 5.1 × 10-3 yielding ∑SrI(A1/2+A3/2+B)=2.4 × 10-2. As only the X, A and B states SrI are accessible on reaction, assuming that the removal of Sr(53PJ) occurs totally by chemical removal, this yields an upper limit for the branching ratio into the ground state of ca. 98%. The present results are compared with previous time-resolved measurements on excited states of strontium halides that we have reported on various halogenated species resulting from reactions of Sr(53PJ), together with analogous chemiluminescence studies on Sr(3PJ) and Ca(43PJ) from molecular beam measurements.

Ultrasonic Signals Generated by a Laser Source in Film/Substrate Systems

1999 ◽  
Author(s):  
T. W. Murray ◽  
Z. Guo ◽  
S. Krishnaswamy ◽  
J. D. Achenbach
Keyword(s):  
Mechanical Properties ◽  
Time Domain ◽  
Michelson Interferometer ◽  
Pulsed Laser ◽  
Laser Source ◽  
Laser Generation ◽  
Ultrasonic Signals ◽  
Acoustic Wave Generation ◽  
The Time Domain ◽  
Film Substrate

Abstract A model for the pulsed laser generation of ultrasound in an isotropic film on a semi-infinite substrate is presented. The model gives the time domain displacement of the system as a function of the density and mechanical properties of the film and substrate and the thermal properties of the film. Theoretical signals are calculated and analyzed for both a slow layer on a fast substrate and a fast layer on a slow substrate. The model has been verified experimentally using a 1 ns Nd:YAG laser source for acoustic wave generation and a stabilized Michelson interferometer for detection. Experimental and theoretical signals agree well for both fast on slow and slow on fast systems.

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