Transcript doppler.ppt

Doppler Free Spectroscopy by
Masked Imaging
Vasiliy Goncharov, Nuradhika Herath, Andres Arregui and Arthur G. Suits
Department of Chemistry
Wayne State University
Detroit MI 48202
Doppler free spectroscopy
• Elimination of one-photon or multi-photon Doppler
broadening
• Use only one laser beam
• This technique involves masking the detector under
the velocity map conditions
Ion Imaging
• Developed in 1987, ion imaging allows the detection of single
product quantum states with sufficient velocity resolutions
• Variants
Velocity mapping
Slice imaging
D. Chandler, P. Houston, J. chem. Phys, 87, 2, 1445
http://ms.cc.sunysb.edu/~asuits/pages/research.html
Experiment
W
to
unmasked full ion cloud
signal
For  ≥ W/2 Ion count is multiplied by /(2arcsin{W/2})
For  < W/2 nothing is done
Applications
CO from Acetone
CH3COCH3 + hv
B 1+(v=0)X 1+(v=0) REMPI spectra of CO
2CH3 + CO
0.6 cm-1
CO+
B 1Ʃ+
X 1Ʃ+
1 cm-1
Hot CO from OCS
B 1+(v=0)X 1+(v=0) REMPI spectrum of CO
Constants
Ref.Values
(cm-1)
Present work
(cm-1)
B0
1.948186
1.948112(6)
D0.106
6.6355(12)
6.6873(30)
H0.1011
-2.161(19)
-1.492(36)
Rotational Analysis: E= 86916.18+ (Bo’ -Bo”)J(J+1)-(Do’ -Do”)J2(J+1)2+(Ho’ -Ho”)J3(J+1)3
V. McKoy and coworkers, JCP, 116, 7, p.2776, 2002
O atom
H atom
O3 + hv
1S
O2 + O (3P)
3P
0
3P
1
3P
2
3P
0
3P
1
3P
2
2P
2P
3/2
2P
1/2
2S
1/2
Summary
•
•
•
•
Use only one laser
Eliminate one photon or multi photon Doppler broadening
Applicable to ionization only
Cannot use for LIF
Acknowledgment
Funding:
DOE-BES