Pranawa C. Deshmukh

Bio: Pranawa C. Deshmukh is an academic researcher from Indian Institutes of Technology. The author has contributed to research in topics: Photoionization & Random phase approximation. The author has an hindex of 19, co-authored 155 publications receiving 1272 citations. Previous affiliations of Pranawa C. Deshmukh include Dr. Hari Singh Gour University & Indian Institute of Science.

Breakdown of the Independent Particle Approximation in High-Energy Photoionization

Abstract: The independent particle approximation is shown to break down for the photoionization of both inner and outer nl (l > 0) electrons of all atoms, at high enough energy, owing to interchannel interac ...

Room Temperature Ferromagnetism and Optical Limiting in V 2 O 5 Nanoflowers Synthesized by a Novel Method

Abstract: We report on the observation of room temperature ferromagnetism as well as optical limiting in V2O5 nanoflower structures synthesized by a simple and novel cost-effective low-temperature method. The flowers are characterized thoroughly by various analytical techniques to ascertain their structure and composition and to confirm the absence of any impurities. The samples exhibit ferromagnetic properties at 300, 200, and 100 K observed from a hysteresis loop. Coercivity for room temperature synthesized V2O5 flowers is 566 Oe at 300 K and is enhanced at 200 and 100 K. We propose a growth mechanism of the flowers and attribute the origin of ferromagnetism to the introduction of oxygen vacancies in accordance with theoretical predictions available on other oxide nanomaterials. The samples also show optical limiting behavior arising from an effective three photon absorption mechanism as demonstrated by a Z-scan experiment for characterization of optical nonlinearity.

Beyond the dipole approximation: angular-distribution effects in valence photoemission

Abstract: Angular distributions of valence photoelectrons showing effects due to higher-multipole photon interactions have been measured for the first time. Neon 2s and 2p photoemission exhibits effects beyond the dipole approximation throughout the 250 - 1200 eV photon-energy range studied. The results suggest that any photoemission experiment, on any sample, can be affected at relatively low photon energies, pointing to a general need for caution in interpreting angle-resolved-photoemission measurements.

Photoionization of group-IIB elements

Abstract: Theoretical photoionization cross sections, angular distributions, and spin-polarization parameters for outer ns and (n-1)d subshells of the group-IIB elements zinc, cadmium, and mercury are determined above their respective (n-1)d thresholds. Account is taken of electron-electron correlation and of the spin-orbit interaction by means of the relativistic random-phase approximation. Comparisons are made with previous theoretical work and with available experimental measurements.

Attosecond time delay in the photoionization of endohedral atoms A@C 60 : A probe of confinement resonances

Abstract: The effects of confinement resonances on photoelectron group delay (Wigner time delay) following ionization of an atom encapsulated inside a ${\text{C}}_{60}$ cage have been studied theoretically using both relativistic and nonrelativistic random phase approximations. The results indicate clearly the resonant character of the confinement oscillations in time delay of the $4d$ shell of Xe@${\text{C}}_{60}$ and present a most direct manifestation of Wigner time delay. These oscillations were missed in a previous theoretical investigation of Ar@${\text{C}}_{60}$ [Phys. Rev. Lett. 111, 203003 (2013)].

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation.

Abstract: The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the functi...

Relativistic Quantum Chemistry

Abstract: Publisher Summary This chapter provides a summary of the relativistic calculations on multielectron or multicenter problems. The Dirac–Fock Hamiltonian and the main quantum electrodynamical (QED) corrections are discussed and the atomic and bandstructure calculations are reviewed. Then the construction of relativistic molecular orbitals and the solvable one-electron molecular and solid-state models are described. The simplest possible system for studying relativistic effects in chemical bonding is H2+. Several variational linear combinations of atomic orbitals (LCAO)-type solutions of the Dirac equation for H2+ show that the relativistic effects decrease the electronic energy by about –7 ╳ 10–6 a.u. The Dirac-Fock and Dirac-Slater molecular calculations, the relativistic semiempirical methods, and the perturbation treatments of relativistic effects are also described. In relativistic treatments of several spectroscopic properties, the entire formulation must be changed if relativistic wavefunctions are used. Some of its examples are considered. The chapter also presents a preliminary account of the relativistic effects on the chemical properties of the periodic system of elements.

Photoionization of atoms using synchrotron radiation

Abstract: A comprehensive review is given on photoionization of rare gas atoms using monochromatized synchrotron radiation. Emphasis is put upon the general experimental and theoretical background, and illustrative examples are presented in order to show the present status and the progress in the field during the last decade.

Nonlinear optical properties of metal nanoparticles: a review

Abstract: Metal nanoparticles (MNPs) hold great technological promise because of the possibility of engineering their electronic and optical properties through material design. One of the effective methods to fabricate MNPs is ion implantation. In this review, recent results on the nonlinear optical properties of nanoparticles (including copper, silver, gold, and bismuth nanoparticles) doped in various bases have been discussed. Some specific optical nonlinear properties, such as nonlinear refraction, two-photon absorption, and optical limiting, for femtosecond, picosecond, and nanosecond laser pulses have also been covered. In addition to ion implantation, we have summarized several other methods for the preparation of composite materials, and Z-scan has been used to study the nonlinear optical properties of these materials.