Electronic Spectra of Aliphatic Carbonyls and Electron-phonon Couplings.

脂肪族单羰基化合物如丙酮和乙醛的刚性基质即使在4.2K下也能产生非常弥散的发射和吸收带。迄今为止，除了晶体中六氯丙酮的T-S吸收和发射光谱之外，还没有报道充分发展的光谱（M.KoyanGII等人，化学物理，5，107（1974））。这种困难的主要原因可能在很大程度上归因于不均匀的加宽，其起源是由于在一个部分中的许多几何形状不同的位点和在另一部分中的光照射期间产生的杂质。目前的工作开始于一个计划，即尽可能减少后一个问题。为此，在光学测量期间，使用同步马达以约5 mm/min的速度提升4.2 K下的单羰基化合物的晶体样品。这对丙酮晶体部分有效：清晰地观察到间距为300- 400 cm-1的谱带<-1>。使用如此大的样品池（50 mm phi x 100 mum）、样品池的波动、氦气鼓泡等技术困难使我们无法观察到良好的S/N信号。除此之外，还观察到六氯丙酮的S_1*S_0吸收光谱。对刚性基质中苄基自由基的一系列系统研究，有助于我们考虑光照射时产生的杂质在主体体系中的作用。

Rigid matrices of aliphatic mono-carbonyls, such as acetone and acetoal-dehyde, generally give rise to very diffuse emission and absorption bands even at 4.2 k. No well-developped spectra have so far been reported except for the T-S absorption and emission spectra of hexachloroacetone in the crystal (M.KoyanGII et al., Chem.Phys., 5,107 (1974)). The main reason for this difficulty may greatly be attributed to inhomogeneous broadening whose origins are due to many geometrically different sites in one part and impurities produced during light irradiation in another part. The present work started with a plan that the latter problem was diminished as best as possible. For this purpose, crystal samples of mono-carbonyls at 4.2 k were lifted up at a speed of about 5 mm per minute using a synchronous motor during the optical measurements. This worked in part for acetone crystals : a band with a spacing of 300-400cm^<-1> was clearly observed. Technical difficulties coming from using such a large sample cell(50mm phi x 100mum), fluctuation of the sample cell, helium bubbling, etc. prevented us from ob-serving good S/N signals. Apart from this partial success, a well-developed S_1*S_0 absorption spectrum of hexachloroacetone was observed similarly. Asystematic series of research on the benzyl radical in the rigid matrices were very useful for us to take into account the role of impurities produced upon light irradiation in the host system.