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

Extraction of alignment parameters from circular dichroic photoelectron angular distribution (CDAD) measurements

In a previous paper, we showed that circular dichroism in photoelectron angular distributions (CDAD) can be used to probe alignment in gas phase atoms and linear molecules. Often this alignment is parametrized through the moments of alignment A(2), A(4), etc., which are commonly extracted from fluorescence polarization measurements. In this paper we show how these can be simply extracted from CDAD spectra. This technique can be used in principle to extract the moments to any order

(1+ 1) CDAD: A new technique for studying photofragment alignment

We report a new technique for measuring photofragment alignment in the gas phase by observing circular dichroism in photoelectron angular distributions (CDAD). This technique is well suited for determining the gas phase alignment of linear molecules. The experiment involves excitation of the photofragment with linearly polarized light followed by photoionization with left or right circularly polarized light. The difference between the photoelectron angular distributions for these two cases is the CDAD spectrum. By measuring CDAD through two different excitation branches, one can obtain the ground state photofragment alignment A(2)0 using a simple analytical formula independent of the photoionization dynamics

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

Strategies for Improving Indian Railways’ Market Share of Port Based Coal Traffic: A Diagnostic Study

India is a vast country. After its independence in 1947, it steadily lost its position in international trade. With the beginning of economic liberalization in 1991, it has taken new initiatives in integrating itself with the world economy. Import restrictions have been removed for many commodities. One of the major impacts of liberalization has been on infrastructure: railways, roadways, ports and airports. Significant changes have also taken place in the composition of imported and exported commodities. Due to these changes, new challenges are being faced on the infrastructure front. One of the challenges is to rectify the mismatch of available infrastructure at ports where a modal change of commodities that are either imported or exported takes place. This paper examines such issues with a specific focus on improving infrastructure required for integration of railways and ports. This is achieved by focusing on coal which is a commodity that (i) brings significant revenues to Indian Railways, and (ii) is witnessing increasing imports. In this diagnostic study, we discuss the problems faced by Indian Railways and identify ways to increase its market share of coal movement between ports and the hinterland.

(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

Protection strategies for next generation passive optical networks -2

Next Generation Passive Optical Networks-2 (NGPON2) are being considered to upgrade the current PON technology to meet the ever increasing bandwidth requirements of the end users while optimizing the network operators' investment. Reliability performance of NG-PON2 is very important due to the extended reach and, consequently, large number of served customers per PON segment. On the other hand, the use of more complex and hence more failure prone components than in the current PON systems may degrade reliability performance of the network. Thus designing reliable NG-PON2 architectures is of a paramount importance. Moreover, for appropriately evaluating network reliability performance, new models are required. For example, the commonly used reliability parameter, i.e., connection availability, defined as the percentage of time for which a connection remains operable, doesn't reflect the network wide reliability performance. The network operators are often more concerned about a single failure affecting a large number of customers than many uncorrelated failures disconnecting fewer customers while leading to the same average failure time. With this view, we introduce a new parameter for reliability performance evaluation, referred to as the failure impact. In this paper, we propose several reliable architectures for two important NGPON2 candidates: wavelength division multiplexed (WDM) PON and time and wavelength division multiplexed (TWDM) PON. Furthermore, we evaluate protection coverage, availability, failure impact and cost of the proposed schemes in order to identify the most efficient protection architecture

Circular dichroism in photoelectron angular distributions from two‐color (1+1) REMPI of NO

A detailed experimental and theoretical study of dichroic effects in photoelectron angular distributions is reported for (1+1), two‐color REMPI of NO via the A^ 2Σ^+, v=0 state. Optically aligned A state rotational levels are probed through ionization by circularly polarized light. Resultant photoelectron angular distributions exhibit significant left–right asymmetry, the phase and magnitude of which are shown to be related to the curvature of the excited state M_J distribution. Theoretical calculations involving a full ab initio treatment of the ionization dynamics result in circularly dichroic angular distribution (CDAD) parameters in good agreement with those derived experimentally. Additional effects including hyperfine depolarization and coherence are also discussed in relation to the observed CDAD data