Hydrogen transfer dynamics in a photoexcited phenol/ammonia (1:3) cluster studied by picosecond time-resolved UV-IR-UV ion dip spectroscopy.
The picosecond time-resolved IR spectra of phenol/ammonia (1:3) cluster were measured by UV-IR-UV ion dip spectroscopy. The time-resolved IR spectra of the reaction products of the excited state hydrogen transfer were observed. From the different time evolution of two vibrational bands at 3180 and 3250 cm(-1), it was found that two isomers of hydrogenated ammonia radical cluster .NH(4)(NH(3))(2) coexist in the reaction products. The time evolution was also measured in the near-IR region, which corresponds to 3p-3s Rydberg transition of .NH(4)(NH(3))(2); a clear wavelength dependence was found. From the observed results, we concluded that (1) there is a memory effect of the parent cluster, which initially forms a metastable product, .NH(4)-NH(3)-NH(3), and (2) the metastable product isomerizes successively to the most stable product, NH(3)-.NH(4)-NH(3). The time constant for OH cleaving, the isomerization, and its back reaction were determined by rate-equation analysis to be 24, 6, and 9 ps, respectively.
D000641:Ammonia / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D008956:Models, Chemical; D019800:Phenol / Q000737:chemistry*; D010777:Photochemistry; D013055:Spectrophotometry, Infrared / Q000295:instrumentation / Q000379:methods; D013056:Spectrophotometry, Ultraviolet / Q000295:instrumentation / Q000379:methods; D013997:Time Factors; D014732:Vibration
D005609:Free Radicals; D019800:Phenol; D000641:Ammonia; D006859:Hydrogen