| Budget Amount *help |
¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1995: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Research Abstract |
Reaction volume changes and enthalpy changes in a photochemical reaction are very important quantities to characterize the reaction. However, a lack of suitable method for detecting these quantities with a sufficiently high sensitivity and high time resolution prohibits our detailed understanding of many chemical reactions. In this study, we have developed new techniques for measuring these quantities with high sensitivity and high time resolution using the so-called 'thermal lens' setup. We have discovered various origins of the lens signals after the photoexcitation, such as the population lens, temperature lens, Kerr lens, and volume lens. By using these components, the reaction volume, enthalpy change, partial molar volume and heat energy form chemical reactions and photophysical processes are successfully measured under a constant temperature, and a constant pressure in a solvent. Therefore we proposed a new name "transient lens method" for these techniques. Furthermore we have discovered various origins for the transient grating signals observed after photoexcitation of organic molecules in solutions, such as temperature grating, cluster grating, and volume grating. By using the grating technique, the translational diffusion process of transient radicals appeared in chemical reactions is investigated. The diffusion constants of the radicals are found to be very small compared with the non-radical molecules with similar sizes and shapes. This anomalous diffusion process is studied in detail by the temperature dependence and molecular size dependence. This study will reveal an interesting field of radicalsolvent intermolecular interaction.
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