New Development in Chemistry of Hypervalent Radicals Approach from the Gas-phase

为了揭示超价自由基在化学反应包括生物化学反应中的作用，我们进行了以下三个方面的研究.用光电子能谱（PES）研究了Na-2^-（H_2O）_n（n = 6）的电子结构，探讨了钠聚集体在小水团簇中的溶剂化作用，通过对Na_2的阴离子到中性基态和第一激发态跃迁的PES谱带的分析，（1^1_g^+）和Na_2（1^3_u^+）的电子结构发现，Na_2-Na^+（H_2O）_n^-型电子态随团簇尺寸的增大而增大，这可以看作是Na_2的溶剂化和水合Na的电离的标志。用ArF准分子激光光解氨-甲醇混合团簇产生的NR_4（CH_3OH）_m（NH_3）_n自由基的电离势（IPs）由光电离阈值测量得到。随着氨和甲醇溶剂数量的增加，观察到的IP显示不同的演变。利用飞秒脉冲激光时间分辨泵浦-探测方法研究了氨-甲醇混合中性团簇光解产生的NH_4（CH_3OH）_m（NH_3）_n团簇的形成和弛豫动力学。通过对质子化团簇离子NH_4（CH_3OH）_m（NH_3）_n的时间演化过程的详细分析，建立了质子化团簇离子的动力学模型.本文报道了一台由喷雾电离源和变温多极子阱组成的光解谱仪，用于研究不同温度下气相生物分子离子的结构和反应性。研究了质子化的丙氨酸色氨酸（Ala-TrpH+）和色氨酸甘氨酸（Trp-GlyH+）的紫外（UV）和红外（IR）光解光谱，探讨了质子对二肽电子结构和反应活性的影响.

In order to reveal the role of hypervalent radicals in chemical reactions including those in biological chemistry, we have studied on the following three subjects.1. The electronic structures of Na-2^-(H_2O)_n (n〓6), which have a similar loosely-bounded electron to NH_4 have been investigated by a photoelectron spectroscopy (PES) to examine the solvation of sodium aggregates in small water clusters, From the analysis of the PES bands for the transitions from the anion to the neutral ground and first excited states derived from Na_2 (1^1Σ_g^+) and Na_2(1^3Σ_u^+) it is found that the Na_2-Na^+(H_2O)_n^-type electronic state grows with increasing cluster size, which can be regarded as a sign of the solvation of Na_2 with ionization of the hydrated Na.2. Ionization potentials (IPs) of NR_4(CH_3OH)_m (NH_3)_n radicals produced by an ArF excimer laser photolysis of ammonia-methanol mixed clusters are determined by the photoionization threshold measurements. The observed IPs show the different evolutions with increasing the number of ammonia and methanol solvents. We have also examined the formation and relaxation dynamics of NH_4(CH_3OH)_m(NH_3)_n clusters produced by photolysis of ammonia-methanol mixed neutral clusters using a time-resolved pump-probe method with femtosecond pulse lasers. From the detailed analysis of the time evolutions of the protonated cluster ion, NH_4(CH_3OH)_m(NH_3)_n, the kinetic model is constructed.3. A photodissociation spectrometer, containing a spray ionization source and a temperature-variable multipoleion trap, has been constructed to examine the structure and reactivity of gas phase biological molecular ionsat various temperatures. Ultraviolet (UV) and infrared (IR) photodissociation spectra of protonatedalanyltryptophan (Ala-TrpH+) and tryptophanylglycine (Trp-GlyH+) have been investigated to examine the effect of proton on the electronic structure and reactivity of the dipeptides.