Reflection Spectrum and Structure in the Exciton Absorption Peak of NaCl and KCl

Abstract

Measurements in the vacuum ultraviolet have been made on the transmission of thin films of NaCl and KC1 and on the reQectivity of single crystals of these same salts. Comparison is made between the two types of measurements and with the absorptions measured in thin films by Schneider and O'Bryan. The agreement with the latter in the case of NaC1 is good only over the region of the first absorption while in the case of KC1 it is good over the whole region over which the measurements overlap. A new absorption is found in NaCl near 1100 A and in KCl just below 1000 A. In both salts the first fundamental absorption near 1600 A, presumed to be that of the exciton, as inferred from the reactivity is at least a doublet at liquid nitrogen temperatures; but further multiplicity of the type predicted by Overhauser is not established, although possibly indicated. Absolute reflectivities oi the order of 60% are measured at low temperatures.

Theory and Applications of Diffuse Reflectance Spectroscopy

“…That this assumption is improper may be illustrated first by the work of Hartman, Nelson, and Siegfried [6], who examined the thin-film absorption and single-crystal reflectivity of KCl (Fig. 8).…”

Solid state core-exciton dynamics in NaCl observed by tabletop attosecond four-wave mixing spectroscopy

“…The relative intensities of the doublet peaks are widely known to deviate from the 2:1 ratio expected by considering state multiplicity [19,[21][22][23][24]26]. Onodera and Toyozawa [24] introduce exchange interaction between the electron and hole, which results in increased mixing of the excited electron and core-hole states, to account for the different doublet peak intensity ratios.…”

“…They are the simplest ionic solids, consisting of equal numbers of monovalent cation-anion species. Decades of investigations on the shortrange interactions of bound electron-core-hole pairs in these materials (core-level excitons or "core-excitons") have aimed to characterize the nature of core-exciton states formed in alkali halides, such as NaCl [18][19][20][21][22][23][24][25][26][27][28][29][30], where some are associated with Na + and some with Cl − . Weak dielectric screening inherent to wide gap insulators enhances electron-hole attraction; the highly localized electronic structure of the core-exciton approaches that of a Frenkel exciton [17,18,27,31].…”

Etude spectrophotométrique des produits formés au cours de l'oxydation superficielle d'alliages de nickel

“…Cette technique se prete bien a l'etude des centres colores dans les solides (3,4) Abstract. The diffuse reflectance spectra obtained on products formed during the superfidal oxidation of various nickel alloys present absorption maxima for the same wavelengths as the spectra obtained on the NiO formed during the oxidation of pure nickel.…”