Radiationless transition in large isolated molecules: Variation of excess energy dependence of its decay rate with initially prepared electronic state

1973 ◽  
Vol 58 (3) ◽  
pp. 1247-1248 ◽  
Author(s):  
E. C. Lim ◽  
Cheng‐Schen Huang
Keyword(s):  
Decay Rate ◽  
Electronic State ◽  
Energy Dependence ◽  
Excess Energy ◽  
Radiationless Transition ◽  
Isolated Molecules

Phosphorescence Lifetime of S02 in the ã3B1 State at Low Pressure

1975 ◽  
Vol 53 (14) ◽  
pp. 2133-2139 ◽  
Author(s):  
J. Philip Briggs ◽  
Robert B. Caton ◽  
Michael J. Smith
Keyword(s):  
Decay Rate ◽  
Electronic State ◽  
Rate Constant ◽  
Pressure Range ◽  
Low Pressure ◽  
Nonradiative Relaxation ◽  
Phosphorescence Lifetime ◽  
Pressure Decay ◽  
Emission Decay ◽  
Spherical Container

The emission decay rate (inverse lifetime) of the optically-excited ã3B1 electronic state of SO2 vapor at approximately 25 °C has been measured in a 35 cm diameter spherical container over the pressure range 1 < P < 500 m Torr in pure SO2 and in mixtures of SO2 with He, Ar, or Xe. The Stern–Volmer rate constant for quenching by [Formula: see text]was determined to be (4.46 ± 0.11) × 108 1 mol−1 s−1, and the extrapolated, zero-pressure decay rate was calculated to be (3.75 ± 0.58) × 102 s−1. The latter quantity implies a considerably greater proportionate contribution by radiative, as opposed to nonradiative, relaxation of this state than has been reported previously.

scholarly journals Fluorescence Property and its Magnetic Field Dependence Across the Photodissociation Threshold of CH3CHO and CD3CDO in a Supersonic Jet

1994 ◽  
Vol 13 (3-4) ◽  
pp. 207-222 ◽  
Author(s):  
Nobuhiro Ohta
Keyword(s):  
Magnetic Field ◽  
Excitation Energy ◽  
Triplet State ◽  
Energy Dependence ◽  
Level Density ◽  
Excess Energy ◽  
Zero Field ◽  
Statistical Limit ◽  
Fluorescence Characteristics ◽  
Dissociation Threshold

Fluorescence characteristics of jet-cooled acetaldehyde at zero field is confirmed to change from the small molecule behavior to the statistical limit behavior in CH3CHO and to the intermediate case in CD3CDO, as the excitation energy increases across the dissociation threshold located below 320 nm. The excitation energy dependence both of the intensity and of the lifetime of the slow fluorescence shows that the dissociation rate becomes faster abruptly with increasing excess energy above the threshold, and the excess energy dependence above the threshold seems to be more drastic in CH3CHO than in CD3CDO. External magnetic field as well as the dissociation in the triplet state plays a role to increase the level density of the triplet state coupled to S1. On excitation below the dissociation threshold, the magnetic quenching of fluorescence becomes more efficient with increasing excess energy and the efficiency of the quenching is larger in CD3CDO than that in CH3CHO by a factor of about 2. On excitation above the threshold, however, the efficiency becomes lower with increasing excitation energy. Thus, the magnetic field effects on fluorescence also change drastically across the dissociation threshold.

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