Three-photon resonant four-photon ionization of H_2 via the C^1 ∏_u state

Ab initio calculations are presented for the vibrational branching ratios in three-photon resonant four-photon ionization of H_2 via the C^1Π_u state. Energy and internuclear distance dependences of the boundfree electronic transition matrix element are explicitly included to estimate deviations from the Franck-Condon approximation. While our calculated branching ratios confirm certain important trends seen experimentally, some differences remain

Photoionization cross sections of rovibrational levels of the B^1Σ^+_u state of H_2

We report theoretical cross sections for direct photoionization of specific rovibrational levels of the B ^1Σ^+_u electronic state of H_2. The calculated cross sections differ considerably from values recently determined by resonant enhanced multiphoton ionization (REMPI) studies. In an attempt to understand the disagreement, we analyze in detail the REMPI dynamics and find that the multiphoton ionization probability is extremely sensitive to the spatial and temporal profiles of the laser pulses. Accurate characterization of laser profiles and their jitter is therefore necessary for a comparison between theory and experiment

Comment on 'Non-equilibrium thermodynamics of light absorption'

A recent paper by Meszéna and Westerhoff (1999 J. Phys. A: Math. Gen. 32 301) has aimed to address what is referred to as a principal question of biological thermodynamics, the possibility of describing photosynthesis in terms of non-equilibrium thermodynamics. The issue is associated with a misrepresentation of the fundamental photophysics involved, and as a result the analysis is invalid

(2+1) resonant enhanced multiphoton ionization of H_2 via the E, F^(1)Σ^+_g state

In this paper, we report the results of ab initio calculations of photoelectron angular distributions and vibrational branching ratios for the (2+1) REMPI of H_2 via the E, F^(1)Σ^+_g state, and compare these with the experimental data of Anderson et al. [Chem. Phys. Lett. 105, 22 (1984)]. These results show that the observed non‐Franck–Condon behavior is predominantly due to the R dependence of the transition matrix elements, and to a lesser degree to the energy dependence. This work presents the first molecular REMPI study employing a correlated wave function to describe the Rydberg–valence mixing in the resonant intermediate state

Optical properties and electronic structure of β′−NiAl

The optical constants and their temperature derivatives have been determined for β′−NiAl from absorption and thermoreflectance measurements in the energy range of 0.2-4.4 eV. The results are interpreted using the self-consistent energy bands of Moruzzi, Williams, and Gelatt. By comparing a calculated joint density of states with ε2, the imaginary part of the dielectric function, good overall agreement is found between theory and experiment. In contrast to earlier analyses, it is found that the 2.5-eV peak in ε2 is primarily due to direct interband transitions terminating near the Fermi surface. This new interpretation of the 2.5-eV feature is discussed in relation to previously reported concentration effects and the rigid-band model

An Improved Approximate Consensus Algorithm in the Presence of Mobile Faults

This paper explores the problem of reaching approximate consensus in synchronous point-to-point networks, where each pair of nodes is able to communicate with each other directly and reliably. We consider the mobile Byzantine fault model proposed by Garay '94 -- in the model, an omniscient adversary can corrupt up to $f$ nodes in each round, and at the beginning of each round, faults may "move" in the system (i.e., different sets of nodes may become faulty in different rounds). Recent work by Bonomi et al. '16 proposed a simple iterative approximate consensus algorithm which requires at least $4f+1$ nodes. This paper proposes a novel technique of using "confession" (a mechanism to allow others to ignore past behavior) and a variant of reliable broadcast to improve the fault-tolerance level. In particular, we present an approximate consensus algorithm that requires only $\lceil 7f/2\rceil + 1$ nodes, an $\lfloor f/2 \rfloor$ improvement over the state-of-the-art algorithms. Moreover, we also show that the proposed algorithm is optimal within a family of round-based algorithms

Mid-Infrared Ethane Emission on Neptune and Uranus

We report 8- to 13-micron spectral observations of Neptune and Uranus from the NASA Infrared Telescope Facility spanning more than a decade. The spectroscopic data indicate a steady increase in Neptune's mean atmospheric 12-micron ethane emission from 1985 to 2003, followed by a slight decrease in 2004. The simplest explanation for the intensity variation is an increase in stratospheric effective temperature from 155 +/- 3 K in 1985 to 176 +/- 3 K in 2003 (an average rate of 1.2 K/year), and subsequent decrease to 165 +/- 3 K in 2004. We also detected variation of the overall spectral structure of the ethane band, specifically an apparent absorption structure in the central portion of the band; this structure arises from coarse spectral sampling coupled with a non-uniform response function within the detector elements. We also report a probable direct detection of ethane emission on Uranus. The deduced peak mole fraction is approximately an order of magnitude higher than previous upper limits for Uranus. The model fit suggests an effective temperature of 114 +/- 3 K for the globally-averaged stratosphere of Uranus, which is consistent with recent measurements indicative of seasonal variation.Comment: Accepted for publication in ApJ. 16 pages, 10 figures, 2 table

Shape resonances in the photoionization of cyanogen

We have studied the photoionization cross sections and photoelectron asymmetry parameters for ionization of the 1pig(X 2Pig), 5sigmag(A 2Sigma + g), and 4sigmau(B 2Sigma + u) levels of cyanogen using frozen-core Hartree–Fock photoelectron continuum orbitals. The main purpose of these studies has been to extend our understanding of the dynamics of shape resonances from earlier studies of diatomic and smaller polyatomic molecules to a larger polyatomic system. The results do, in fact, reveal a rich shape resonant structure in the electronic continuum of this polyatomic system. There is a low-energy sigmau resonance which, as expected, is the C–C analog of the l=3 shape resonance seen in N2(3sigma - 1g) and several other diatomics. In contrast to this diatomic-like behavior, the presence of the two CN groups in C2N2 results in a second sigmau and a sigmag resonance corresponding to linear combinations of a l=3 shape resonance localized on the CN sites. Moreover, our results also show a pronounced shape resonant behavior in the piu continuum, which, to our knowledge, has not been seen in smaller molecules