Selenium optical constants

Fig. 5.5. Optical conductivity a-(a>) of liquid selenium at constant pressures of 400 bars (solid curves, Ikemoto et al., 1994) and 300 bars (dashed curves, Seyer et al., 1986).

Fig. 2.7. Pressure-temperature phase diagram of selenium showing solid, liquid, and vapor phases together with regions of semiconducting (SC), metallic (M), and insulator (I) behavior. The line of semiconductor-metal transitions observed in the liquid at high pressure (Brazhkin et al., 1989) is extrapolated to contour of constant DC electrical conductivity (

Fig. 5.4. Real part of the dielectric function i(t >) (solid lines, left-hand scale) and optical conductivity o-(a)) (dotted lines, right-hand scale) for liquid selenium at various temperatures and a constant pressure of 300 bar (Seyer et al., 1986).

Fig. 5.6. Temperature-dependent energy gap Eg of liquid selenium determined from optical measurements at various constant pressures (Hosokawa and Tamura, 1990b).

The energy gap, Eg = Fis(f)-X3, varies with the lattice constant according to E = E°-3.9 (ao aj) with Eg = 0.60eV and ao = 6.20A. Literature data for the bulk modulus of K = 400 or 520 kbar yield dEg/dp = -20.2 and -15.5 meV/kbar, respectively, Farberovich [1]. The dependence on hydrostatic pressure dEg/dp= -11 meV/kbar is derived from optical absorption spectra by Kirk etal. [21], see also Jayaraman et al. [22,23,24]. The value -12meV/kbar is reported by Chatterjee et al. [25], and -14.8 meV/kbar by Bucher et al. [14] calculations with a model based on the compressibility curves of samarium and selenium ions give -7.7 meV/kbar, Narayan, Ramaseshan [16]. The deformation potential, 2 = (dEg/dp)Ko (with Ko=bulk modulus at room temperature), is -5.7 eV, Jayaraman etal. [22], also see [23, 24]. 

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