A digital technology for scanning the luminescent characteristics of alkali halide crystals

A digital technology for scanning the X-ray luminescence, tunnel luminescence, and thermostimulated luminescence spectra in the spectral range from 200 nm to 850 nm is experimentally demonstrated using the example of a NaCl crystal, which is part of the group of alkali halide crystals. This is done with the specified spectrum intervals and scanning speed using a high-aperture monochromator MSD-2 and a photoelectronic multiplier type H 8259 of the company “Hamamatsu”, operating in the photon counting mode, controlled by special programs SpectraScan and ThermoScan. The obtained experimental data are digitally converted for further processing of the graphical representation of the results using the OriginPro software package, which allows you to draw up graphical dependencies of the spectra and perform their mathematical processing.

Accounting for the Local Field When Determining the Dielectric Loss Spectra of Metals in the Region of the Frequencies of Volume, Surface and Localized Plasmon Oscillations

The optical constant of bulk metal is used to determine the dispersion of the local field under one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) confinement. 3D confinement, expressed as ε 2 m i c ( ω 3 D ) , corresponds to the dielectric loss spectra of spherical particles with a diameter, d, much less than the wavelength of the beam used to measure the spectrum (d << λ). Excellent agreement with the results of Mie theory and experimental data for solid colloids within alkali halide crystals was observed. The function expressed as ε 2 m i c ( ω 1 D ) allows the measurement of spectral micro-characteristics in the frequency range of the longitudinal collective motion of the free electrons. This corresponds to the spectrum of dielectric losses of bulk plasma oscillations. The function ε 2 m i c ( ω 2 D ) describes the spectra of the dielectric losses of surface plasma oscillations in thin metal films. It is shown that the peak positions of ε 2 m i c ( ω 3 D ) , ε 2 m i c ( ω 2 D ) and ε 2 m i c ( ω 1 D ) spectra for simple metals, viz. alkali metals as well as Al, Be, Mg, Ga, In, Sn and Si, are in agreement with experimental results from electron-energy-loss spectroscopy and various optical techniques.

Optical Properties of Alkali Halides in Ultraviolet Spectral Regions

The optical reflectance spectra of alkali halide crystals KI and RbI were measured over the energy range of 4.14 to 6.91 eV. Both single crystal and poly-crystal samples were used to accomplish this task. The phase θ ( ω ) was computed using the Kramers-Kronig relation between the real and imaginary parts of the complex function, ln r = ln | r | + i θ ( ω ) . Subsequently, the optical constants n and κ were determined from the Fresnel reflectivity equation. The real and imaginary parts of dielectric constants ε 1 and ε 2 were then calculated using n and κ. The optical absorption spectra of the crystal have also been measured in these spectral regions. The spectra agree reasonably well with the current theory concerning exciton peaks. In addition, a shoulder was found in the spectra similar to those previously seen and associated with the band-to-band transition in the alkali iodides.