Ultrafast Proton Transfer Reaction Dynamics in Phenol−Ammonia Cation Complex

• Main Authors: Chen, Yi-Wei, 陳依微
• Other Authors: Cheng, Po-Yuan
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/69261555863718326242

碩士 === 國立清華大學 === 化學系 === 99 === We report studies of ultrafast proton transfer reaction of PhOH−NH3 cation complex using femtosecond photoionization- photofragmentation spectroscopy.With 266 nm ionization, the observed transients for PhOH−NH3 cation complex are characterized by an ion depletion with an initial spike and two time constants of about 0.8 ps and 40 ps. The results support the mechanism in which PhOH−NH3 cation complex initially undergoes a fast vibrational dephasing or wave packet motion causing the proton wandering between O and N. Then, PhO undergoes a fast intramolecular vibrational energy redistribution (IVR) in about 0.8 ps. Due to a large structure change upon ionization, a large amount of vibrational energy mainly deposited in the reaction center:O⋯H⋯N. It takes about 40 ps to dissipate the energy along the pronton transfer coordinate to other vibrational modes and then the cation relaxes into the equilibrium structure. We also compare dynamics in complexes with different Lewis bases. The results also support the mechanism defined in PhOH−NH3 cation complex and suggest the proton affinity of bases being an important factor for the proton-transfer affect dynamics in complex.