Photoelectron spectra of polysilanes

Some organopolysilanes (high-molecular-weight polymers which only contain silicon atoms in their backbone) can be used as highly sensitive, self-developing uv photoresists. To understand the electronic structure of polysilanes and help rationalize their solid-state uv photosensitivity, we have recorded the photoelectron spectra of several polysilanes: poly({β}-naphthylmethylsilane), poly(phenylmethylsilane, poly(n-dodecylmethylsilane, and poly(n-propylmethylsilane). We find that if the polymer photoemission spectra can be described in terms of backbone Si-Si and side-chain Si-C levels which do not hybridize (as in the alkyl polysilanes), then the solid-state uv sensitivity of the polymer is high. An explanation of this correlation in terms of the degree of hybridization of the low-lying bonding and antibonding Si-Si levels with the levels of the carbon side-group molecule will be presented.