Orientation dependence of X-ray reflection from BNhex in the energy region of B and N K-edges

Local deformation in hexagonal boron nitride crystal near the B K-shell -excitation

“…The analysis of the low-lying excitation (A) in figure 1 shows that (i) its full width at half-maximum (FWHM) amounts to ∼0.32 eV (for comparison, 0.37 eV in [20]), which is typical for an atomic x-ray transition in a solid and supports the conclusions [20] regarding its atomic origin and the nonbonding character of the relevant a 2 MO and (ii) there is an additional structure consisting of a shoulder A centred at 192.4 eV and a peak A at 193.1 eV. This structure was earlier registered in experimental studies [7,20]. To examine the XAπS, its spectral deconvolution is plotted in figure 2.…”

“…For the latter reason, the kinetics of the process has to be taken into consideration. The increase of the intensities of the shoulder A and the line A , for i-BN (i ≡ incoherent phase), observed in reference [7], supports the proposed mechanism, as one can assume a noticeable density of the defect boron sites in a thin film of the metastable incoherent phase BN responsible for the higher intensity of these features relative to the main transition. In fact, Wada and Yamashita have shown that small variations in substrate temperature, laser fluence, ion fluence and gas pressure will produce BN thin films of hexagonal or incoherent structure [36].…”

“…Long-living high-energy excitations in solids are of particular interest for investigations of the atomic dynamics accompanying them. Experimental studies of x-ray absorption, fluorescence and emission spectra as well as the polarization and orientation dependences of the x-ray reflectivity near the B K edge in hexagonal boron nitride (h-BN) crystal [1][2][3][4][5][6][7][8][9][10][11] provide evidence of the appearance of a well resolved, intense and narrow absorption line at 191.8 eV. In the high-energy part of the B K emission, an intense and complex band attributed to the radiative decay of this excitation is observed.…”

Anisotropy of x-ray reflectivity: chemical and structural effects on K-shell excitations in hexagonal BN crystal

“…The angular spectral dependences of the reflection coefficients were carried out at the synchrotron radiation laboratory HASYLAB at the UHV reflectometer using s-polarized synchrotron radiation and in the special chamber attached to the RSM-500 x-ray spectrometermonochromator in which the bremsstrahlung from the tungsten anode of the x-ray tube has been used. Details of both experiments were fully considered in [1][2][3]. Notice that the energy resolution near the B K-absorption edge was 0.7 eV in the experiment with an x-ray tube.…”

“…Up to now the question of the influence of the spatial crystal anisotropy on the x-ray reflection has been kept in the shade. The early experimental studies of the interaction of x-ray radiation with h-BN [1][2][3] show a very strong orientation dependence of x-ray reflectivity and scattering due to crystal orientation with respect to the electric field vector. The aim of this paper is to give a comprehensive analysis of the origin of the orientation dependence of K-shell x-ray reflection (and calculated absorption spectra) near edge structure in the h-BN crystal.…”