Research output: Contribution to journal › Article › peer-review
A quasi-atomic treatment of chemical and structural effects on K-shell excitations in hexagonal and cubic BN crystals. / Franke, R.; Bender, S.; Hormes, J.; Pavlychev, A. A.; Fominych, N. G.
In: Chemical Physics, Vol. 216, No. 1-2, 15.03.1997, p. 243-257.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - A quasi-atomic treatment of chemical and structural effects on K-shell excitations in hexagonal and cubic BN crystals
AU - Franke, R.
AU - Bender, S.
AU - Hormes, J.
AU - Pavlychev, A. A.
AU - Fominych, N. G.
PY - 1997/3/15
Y1 - 1997/3/15
N2 - Experimental and theoretical investigations of the K-shell X-ray absorption near edge structure (XANES) in hexagonal and cubic boron nitride crystals were carried out. A central role is revealed of: (1) the atomic B and N 1s-1 2p resonances in the formation of the main resonance features, (2) the splitting of these atomic excitations by an anisotropic surroundings potential into single π and double degenerated a components in hexagonal relative to cubic BN crystal in which they remain triple degenerated, and (3) the localization region size determining the essential difference between the B and N K-shell excitations. The quasi-atomic approach to inner-shell photoprocesses is applied to compute the XANES. The applicability of molecular models for simulation of the core excitations in the crystals is discussed. It is shown that the B K-excitations are essentially localized within the nearest neighbors whereas the N K ones are more delocalized. The experimental measurements with high energy resolution evidence that the full width at half maximum for the low-lying excitation in h-BN is ≈ 0.37 eV and in its vicinity a near-π-resonance structure containing a shoulder at 192.3 eV and a well-resolved narrow peak at 193.1 eV appears. Its origin is rationalized taking into account the local atomic rearrangement allowing the out-of-plane displacements of excited-core B atoms from their regular positions (polaron mechanism).
AB - Experimental and theoretical investigations of the K-shell X-ray absorption near edge structure (XANES) in hexagonal and cubic boron nitride crystals were carried out. A central role is revealed of: (1) the atomic B and N 1s-1 2p resonances in the formation of the main resonance features, (2) the splitting of these atomic excitations by an anisotropic surroundings potential into single π and double degenerated a components in hexagonal relative to cubic BN crystal in which they remain triple degenerated, and (3) the localization region size determining the essential difference between the B and N K-shell excitations. The quasi-atomic approach to inner-shell photoprocesses is applied to compute the XANES. The applicability of molecular models for simulation of the core excitations in the crystals is discussed. It is shown that the B K-excitations are essentially localized within the nearest neighbors whereas the N K ones are more delocalized. The experimental measurements with high energy resolution evidence that the full width at half maximum for the low-lying excitation in h-BN is ≈ 0.37 eV and in its vicinity a near-π-resonance structure containing a shoulder at 192.3 eV and a well-resolved narrow peak at 193.1 eV appears. Its origin is rationalized taking into account the local atomic rearrangement allowing the out-of-plane displacements of excited-core B atoms from their regular positions (polaron mechanism).
UR - http://www.scopus.com/inward/record.url?scp=0031569164&partnerID=8YFLogxK
U2 - 10.1016/S0301-0104(96)00374-6
DO - 10.1016/S0301-0104(96)00374-6
M3 - Article
AN - SCOPUS:0031569164
VL - 216
SP - 243
EP - 257
JO - Chemical Physics
JF - Chemical Physics
SN - 0301-0104
IS - 1-2
ER -
ID: 43209764