Ball and stick model of the VH4 centers in silicon or germanium. The Si–H bonds point towards the missing atom along trigonal axes.
Absorption of the stretching modes of (a) VH4 in a sample grown in H2 atmosphere, (b) VD4 in a sample grown in D2 atmosphere. In both spectra, the spectral resolution is 0.04 cm−1. The peak wavenumbers and the relative intensities of the components are indicated in the figures and the spectral spans are the same in (a) and (b).
Absorption of the 2183 cm−1 LVM of VH3 HC in a sample from a crystal with a large C concentration grown in a H2 atmosphere. The spectral resolution is 0.04 cm−1.
Displacement coordinates of the particles for VH4. The origin of each coordinate, marked by a dot, corresponds to the equilibrium of the system. The broken line arrows indicate the directions of the electric dipoles induced by the IR-active normal modes of the center.
Definition of the angles introduced in Secs. III and IV . (a) corresponds to VH4 and VD4 and (b) corresponds to VH3 HC. The heavy broken lines indicate the inter-particles equilibrium distances, whereas the full lines indicate the out of equilibrium inter-particles distances.
Experimental and modeled characteristics of the main lines of the VH4 and VD4 spectra. The experimental values are at 6 K. χ = 1.2 and natural abundances of the Si isotopes have been used. Model 1 considers only centers involving three or four 28Si whereas model 2, described in Appendix B , considers all possible combinations of the first silicon neighbors. The ratio of the natural abundances of the Si-isotopes are P 29/P 28 = 0.051 and P 30/P 28 = 0.034. The asterisk refers to the line marked by an asterisk in Fig. 2(a) ; this line is explained in the context of model 2.
Experimental and modeled characteristics of the three main lines in the spectrum of VH4 trapped by carbon. The experimental values are at 6 K. χ = 1.2 has been used in column 3 and natural abundances of the Si isotopes have been used in column 5.
Modeled wavenumbers (cm−1) and relative intensities of the Si isotopic combinations of the Si–H stretch modes of VH4 in silicon. S is the isotope shift factor and the wavenumber in column 5 is (1 − S) × 2222.97 cm−1. The wavenumbers in column 5 are calculated for χ = 1.2. The intensities in column 6 are expressed in terms of the abundances P 28, P 29, and P 30 of the Si isotopes and those in column 7 are for the natural Si abundances.
Article metrics loading...
Full text loading...