Spin non-conservation in low-energy molecular charge-transfer reactions

✍ Scribed by Eldon E. Ferguson

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 419 KB
• Volume: 99
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(83)80535-1

✦ Synopsis

The reaction HaO*('B) + NOa -HaO['A) + NO:('X) occurs at near the collision rate constant, 1.2 x lo* cm 3 s-l, in spite of the fact that tbc reactants produce both a singlet and a triplet state and the products correlate only with the singlet state. This would be expected to yield ;L statistical weight factor of $ to be multiplied by the collisjon rate constant to obtain the maximum charge-tranfcr rate constant_ The triplet products of the ch.uge transfer are clearly endothermic_ Tbc sin@-triplet intersection has not been identified but the available information about the sin@ and triplet states of the intermediate protonated nitricacid molecule is diicusscd. Four other examplesof app.uent "spin violation"ch.u~e-transfer reactions have been noted, Ha0 +f NO, NaO++ NO. CO'+ NO and C&t + Oa_ l_ lutroduction No cases have been observed to our knowledge of thermdl-energy charge-tranfer reactions in which the rate constant exceeds the collision rate constant, i.e. the rate constant for inwardly spiralling, close colli-sions_ It seems therefore that there isno evidence from measured rate constants for electron tranfer with high probability over distances greater than the capture cross-section impact parameter (typically 5-6 A).