Electronic absorption spectrum isotope effects

Jou FY, Freeman GR. (1979) Temperamre and isotope effects on the shape of the optical absorption spectrum of solvated electron in water. J Phys Chem 83 2383-2387. 

The first report of the absorption spectrum of acceptors in semiconductors is probably the paper by Burstein et al. [26], showing the LHeT transmission spectra of two p-type silicon samples. In one of these spectra, broad electronic lines, attributed to boron, could be seen at 0.034, 0.040 and 0.043 eV while in the other, from a nominally undoped sample, lines near 0.055 and 0.06 eV were observed, now known to be due to the aluminium acceptor. Since then, many acceptors have been identified in silicon and other semiconductor crystals and with the same technological incentive as for donors, their optical spectroscopy has been widely used to characterize them, evaluate their concentrations, provide physical insight into the VB structures of the crystals and more recently evaluate the effect of impurity isotope broadening in quasi-monoisotopic crystals. 

An inverted version of the messenger tagging technique for detecting ion absorption uses the fact that electronic and/or vibrational excitation of ions hinders formation of weakly-bound clusters. This effect, explored years ago in relation to laser isotope separation [82], has recently been demonstrated for spectroscopy of N2" ions, cooled to 10.6 K in a 22-pole trap by collisions with He and termed laser-induced inhibition of cluster growth (LIICG) [83]. An electronic spectrum is generated by monitoring the reduction of the steady-state concentration of ion-He complexes as a function of the excitation laser wavenumber. 

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