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Photodegradation mechanisms in laser dyes : A laser irradiated ESR study
| Title: | Photodegradation mechanisms in laser dyes : A laser irradiated ESR study |
| Authors: | Yamashita, Mikio Browse this author | | Kashiwagi, Hiroshi Browse this author |
| Issue Date: | Feb-1976 |
| Publisher: | IEEE: Institute of Electrical and Electronics Engineers |
| Journal Title: | IEEE Journal of Quantum Electronics |
| Volume: | 12 |
| Issue: | 2 |
| Start Page: | 90 |
| End Page: | 95 |
| Publisher DOI: | 10.1109/JQE.1976.1069096 |
| Abstract: | The photodegradation mechanisms in xanthene dye-laser solutions are investigated at 77 K by the direct detection of a decrease in the concentration of dye molecules in the lowest excited triplet state (T1 state) and of free radicals produced after degradation using an ESR technique under UV (3511 + 3638 A) or 5145-Å laser iriadiations. It is shown that the ESR spectral shape of the radicals induced by an UV laser beam is quite different from that of those induced by a 5145-Å beam. For those radicals, the irradiation time and power dependences, the effects of dye and solvent molecular structures and the role of the T1 state by the addition of cyclooctatetraene (COT) quenchers are examined in some detail. As a result the two following laser-induced photochemical reactions are proposed: in UV laser- or flashlamp-pumped dye lasers, the C-H bond rupture of a solvent molecule due to the energy transfer of a dye molecule in a higher excited triplet state, which is produced by a T-T absorption of a dye molecule in the T1 state, results in a radical and a leuco compound of the dye. On the other hand, in the case of the 5145-Å laser excitation, a partially reversible change of a dye molecule in the T1 state produced by only a one-photon absorption results in another radical which depends on the chromophoric structure of the dye. |
| Rights: | © 1976 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/45309 |
| Appears in Collections: | 工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 山下 幹雄
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