Development of molecular spectroscopy with the use of femtosecond light pulses in the near-infrared spectral region

1. bianthryl中电荷转移态的形成bianthryl是由两个由C-C键连接的蒽环形成的。当这个分子吸收光子时，一个电子从一个蒽环迁移到另一个蒽环。这是最基本、最简单的化学反应之一。利用飞秒时间分辨近红外光谱，可以清楚地观察到局域激发态（LE）和电荷转移态（CT）是独立的跃迁态。结果表明，乙腈溶液中二苯基光照射产生的LE态直接转化为CT态。由于探针光的波长比可见光或紫外光谱长，因此可以用透射法将时间分辨近红外光谱应用于散射样品。利用这一优势，首席研究员和他的合作者将飞秒时间分辨近红外光谱应用于更多的氧化钛光催化剂（TIO4，直径20 nm）的粉末样品。他们成功地观察到在1ps内发生的电子弛豫过程，在几十皮秒内发生的电空穴复合过程，以及在2ps内发生的从氧化钛到铂共催化剂的电子迁移过程。这些结果解释了铂共催化剂负载到氧化钛颗粒时催化活性增加的机理。测量了对称和不对称取代双苯基的电荷转移态性质，并对其近红外光谱进行了时间分辨。仅对称取代的双苯基在近红外区观察到CT态吸收带；不对称取代的双苯基没有观察到它们。在近红外区观察到的CT吸收带是两个蒽环之间的电荷共振相互作用。少

1. Formation of charge-transfer state in bianthrylBianthryl is formed by two anthracene rings connected by a C-C bond. When this molecule absorbs a photon, an electron is migrated from one of the anthracene rings to the other. This is one of the most basic and simplest chemical reactions. By using femtosecond time-resolved near-infrared spectroscopy, the locally excited (LE) state and the charge transfer (CT) state are clearly observed as separate transitions. It has been concluded that the LE state generated by the photoirradiation of bianthryl in acetonitrile solution is directly converted to the CT state.2.Carrier dynamics in titanium oxideBecause the wavelength of the probe light is longer than visible or ultraviolet spectroscopies, it is possible to apply time-resolved near-infrared spectroscopy to scattering samples with the transmission method. By using this advantage, the head investigator and his collaborators have applied femtosecond time-resolved near-infrared spectroscopy t … More o the powder samples of titanium oxide photocatalyst (TIO4, 20 nm in diameter). They successfully observed an electron relaxation process that occurs within 1 ps, electro-hole recombination processes in several tens of picoseconds, and an electron migration process from titanium oxide to platinum co-catalyst in 2 ps. The results explain the mechanism of the increase of catalytic activities when platinum co-catalyst is loaded to titanium oxide particles.3.Nature of charge-transfer state of symmetrically and asymmetrically substituted bianthrylsTime-resolved near-infrared spectra of symmetrically and asymmetrically substituted bianthryls have been measured. CT state absorption bands in the near-infrared region were observed only for the symmetrically substituted bianthryls ; they were not observed for the asymmetrically substituted bianthryls. It is strongly suggested that the CT absorption band observed in the near-infrared region represents the charge resonance interaction between the two anthracene rings. Less