PubMed · 4452325
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M Nurminen. 1974. [Statistical evaluation of screening programs].. https://pubmed.ncbi.nlm.nih.gov/4452325/
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The reactions of OH with CS2, OCS, and 3SO and of 3O2 with CS2, SCSOH, and HOSO have been studied by optimizing minima and transition states with B3LYP/6-31+G(d) and carrying out higher-level ab initio calculations on fixed geometries. The combined calculations provide valuable insight into the mechanism for the atmospheric oxidation of CS2. The initial step is the formation of the SCSOH complex (1) which readily adds molecular oxygen to form the SC(OO)SOH complex (8). A key step is the oxygen atom transfer to the sulfur bearing the hydroxyl group which leads directly to OCS plus HOSO. The HOSO + 3O2 reaction has a near zero calculated activation barrier so generation of O2H + SO2 should proceed readily in the atmosphere.
We examined 40 taxa from nine genera within the subfamily Mimosoideae; 29 (73%) from six genera produced carbon disulfide (CS2). In addition, 19 of 40 taxa (48%) produced carbonyl sulfide (OCS). Of nine mimosoid taxa that produced CS2, all possessed a djenkolic acid and a cysteine lyase. Of three mimosoid taxa that did not produce CS2, two lacked a cysteine lyase and one lacked both a lyase and a djenkolic acid. Of 16 taxa from 14 genera from the other two subfamilies of the Fabaceae, the Caesalpinioideae and Papilionoideae, none produced CS2. The results suggest that CS2 production is common in the Mimosoideae and uncommon in the Caesalpinioideae and Papilionoideae and that plants in the Mimosoideae that do produce CS2 must possess both a djenkolic acid and a cysteine lyase for this production to occur.
We have attempted subpicosecond time-resolved absorption spectroscopy of all-trans-beta-carotene in organic solvents in the 820-1060 nm region and found novel transient absorption features which lived in subpicosecond time scales. A first component that appeared immediately after excitation showed a lifetime of 190 +/- 10 fs in n-hexane in agreement with the 1Bu+ lifetime that had been determined by fluorescence upconversion spectroscopy (195 +/- 10 fs). (Kandori et al. [1994] J. Am. Chem. Soc. 116, 2671-2672.) Therefore, this component is assigned to a transient absorption from the 1Bu+ state.