• N Singh

Articles written in Pramana – Journal of Physics

• Electronic structure and activation energy of hydrogen in NEG alloy using nonlinear response theory

Electronic structure of hydrogen in NEG alloy [Zr0.70V0.246Fe0.054] is calculated by using nonlinear response theory [Kohn and Sham,Phys. Rev.A140,1133 (1965)]. The configurational energy is calculated by assuming the ideal hcp structure for NEG alloy. The calculated configurational energy predicts that hydrogen prefers octahedral (0)-site in NEG alloy.s-Type shallow bound state of energy -1.580 x 10-5 Ryd. suggests that hydrogen does not form NEG hydride and it stays as a free ion in NEG alloy. This conclusion confirms the prediction of Tripathiet al.

• Theoretical study of structural energy, phonon spectra, and elastic constants of Rh and Ir

The transition metal pair potential (TMPP) is used to study band structure energy of Rh and Ir. Both metals are found to be most stable in fcc structure down to atomic volume 0.5V0. The pressure at 0.5V0 is found to be 5.235 Mbar and 9.216 Mbar in Rh and Ir, respectively. The TMPP is also used to study other properties of these metals like cohesive energy, phonon frequencies at observed volume. The bulk moduli and elastic constants of these metals at observed volume are calculated by including the volume contribution.

• Working group report: Beyond the standard model

• Inﬂuence of near-edge processes in the elemental analysis using X-ray emission-based techniques

The near-edge processes, such as X-ray absorption ﬁne structure (XAFS) andresonant Raman scattering (RRS), are not incorporated in the available theoretical attenuation coefﬁcients, which are known to be reliable at energies away from the shell/subshell ionization thresholds of the attenuator element. Theoretical coefﬁcients are generally used to estimate matrix corrections in routine quantitative elemental analysis based on various X-ray emission techniques. A tabulation of characteristic X-ray energies across the periodic table is provided where those X-rays are expected to alter the attenuation coefﬁcients due to XAFS from a particular shell/subshell of the attenuator element. The inﬂuence of XAFS to the attenuation coefﬁcient depends upon the atomic environment and the photoelectron wave vector, i.e., difference in energies of incident X-ray and the shell/subshell ionization threshold of the attenuator element. Further, the XAFS at a shell/subshell will signiﬁcantly alter the total attenuation coefﬁcient if the jump ratio at that shell/subshell is large, e.g., the K shell, L3 subshell and M$_5$ subshell. The tabulations can be considered as guidelines so as to know what can be expected due to XAFS in typical photon-induced X-ray emission spectrometry.

• # Pramana – Journal of Physics

Volume 94, 2019
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019