Spectroscopic studies of jet-cooled AINi

Journal ArticleResonant two-photon ionization spectroscopy has been used to interrogate diatomic AlNi produced by laser vaporization of a 1:l alloy target in a supersonic molecular beam of helium. Although a large density of states in this molecule prohibits a concise elucidation of its electronic structure, the presence of discrete transitions has allowed several bands to be rotationally resolved. From the analysis of these bands the ground state has been determined as X 2?5/2, originating from the 3SA3&Nio2 configuration, and the bond length has been measured as 2.3211?0.0007 A. The dissociation energy and ionization potential of AlNi have also been determined as D0( AlNi) =2.29?0.05 eV and I.P. ( AlNi) =6.95?0.09 eV, respectively

Interaction of an aluminum atom with an alkaline earth atom: spectroscopic and ab initio investigations of AICa

Journal ArticleA spectroscopic analysis of diatomic AlCa generated by laser vaporization of a 2:1 AI:Ca metal alloy followed by supersonic expansion has been completed using resonant two-photon ionization spectroscopy. Four excited electronic states have been identified and investigated in the energy region from 13 500 to 17 900 cm-1. These are the [13.5] ?II,, the [15.8] ??, the [17.0] ??3/2(?), and the [ 17.61 2?3/2 states. From rotational analysis excited state bond lengths have been measured for three of the four excited states, and the ground state has been unambiguously determined as a ?II, state with a weighted least squares value of the ground state bond length of r"0 = 3.1479 ? 0.00 10 A. The ionization energy of the molecule has also been directly determined as 5.072?0.028 eV. Ab inirio calculations for the potential energy curves of seven low-lying states of AlCa [X ?IIr, ??+, 4?-, 4IIr, ?II,(2), ??, and X l?+ and for the X 1?+ ground electronic state of AlCa+ have been carried out. In agreement with experiment, ?II, is calculated to be the ground electronic state of the neutral molecule. The dissociation energies of AlCa (X ?II,) into Al(3s?3p?,?Po) +Ca(4s?,?S) and for AlCa+ (X ??+) into A1+(3s?,?S) +Ca(4s?,?S) are calculated to be 0.47 and 1.50 eV, respectively. The excited ??+, 4?-, 4II,, 2II(2), ??, and ??+ states are calculated to lie 0.2, 0.7, 0.7, 1.1, 1.1, and 1.1 eV above X ?IIr,, respectively, and the vertical and adiabatic ionization energies of AlCa have been calculated to be 5.03 and 4.97 eV, respectively

Interaction of an aluminum atom with a closed subshell metal atom: spectroscopic analysis of AIZn

Journal ArticleResonant two-photon ionization spectroscopy has been employed to investigate diatomic AlZn produced by laser vaporization of a 1:2 Al:Zn alloy target disk in a supersonic expansion of helium. Several discrete transitions are reported in the energy range from 18 400 to 19 100 cm-?. Most of these are assigned as members of the B ?II.?x ?II system, although an isolated band has been observed and assigned as the 2-0 band of the A ?' =0.5?X ?II 1/2 system. A pair of strongly mixed levels are identified as resulting from a homogeneous spin-orbit perturbation between the A ?' =0.5, v' =3 and the B ?II1l2, v' = 1 levels, and the perturbation matrix element has been deduced to be 8.11 cm-? for 27 Al64Zn, 8.23 cm-? for 27 Al66Zn. The ground state has been unambiguously identified as a 2rrr state with a bond length of 2.6957?0.0004 ?. Comparisons to the results of the preceding article on the spectroscopy of AlCa are also provided, along with a discussion of the chemical bonding in AlZn in relation to AlCa, AlAr, and AIKr

Spectroscopic analysis of jet-cooled AICu

Journal ArticleDiatomic AlCu has been interrogated using resonant two-photon ionization spectroscopy in a supersonic expansion of helium. The ground state is shown to be X l?+, deriving from the 3&3dgd configuration, in agreement with theoretical predictions. The closed-shell nature of this molecule results in a low density of electronic states, allowing the chemical bonding and electronic structure to be investigated in detail. Five excited electronic states have been observed and characterized, leading to a potential energy diagram based solely on experimental results. Constants experimentally determined for AlCu include a ground state bond length (r0) of 2.3389?0.0004 A, a dissociation energy, Do, of 2.315?0.012 eV, and an ionization potential of 7.065?.014 eV

Spectroscopic analysis of the open 3 d subshell transition metal aluminides: AIV, AICr, and AICo

Journal ArticleThree open 3d subshell transition metal aluminides, AlV, AICr, and AlCo, have been investigated by resonant two-photon ionization spectroscopy to elucidate the chemical bonding in these diatomic molecules. The open nature of the 3d subshell results in a vast number of excited electronic states in these species, allowing bond strengths to be measured by the observation of abrupt predissociation thresholds in a congested optical spectrum, giving D?(AlV)=1.489?0.010 eV, D?(AlCr)=2.272?0.009 eV, and D?(AlCo)= 1.844?0.002 eV. At lower excitation energies the presence of discrete transitions has permitted determinations of the ground state symmetries and bond lengths of AlV and AlCo through rotationally resolved studies, giving r-6 (AlV, ??=O)=2.620?0.004 A and r: (AlCo, ??=3)=2.3833?0.0005 A. Ionization energies were also measured for all three species, yielding IE(AIV)=6.01?0.10 eV, IE(AlCr)=5.96?0.04 eV, and IE(AlCo)=6.99?0.17 eV. A discussion of these results is presented in the context of previous work on AlCu, AlNi, AlCa, and AlZn

A Tailored Systems Engineering Framework for Science and Technology Projects

As government and industry becomes subject to a wider range of technology initiatives, science and technology (S&T) research project leadership recognizes the need to incorporate more systems engineering (SE) rigor into their projects. The objective of this research is to develop a tailorable systems engineering framework for S&T project planning, execution, assessment and transition. The key deliverable is an Excel-based tool instantiating the SE framework for a wide range of S&T projects in technology development organizations. It includes a report with tailored methods based on programmatic discriminants. To develop this framework, a comprehensive understanding of SE principles is applied to several case studies across government and supporting industry-sponsored S&T activities. This research followed a six-step approach: (1) Literature Review; (2) Formulate Taxonomy; (3) Prepare Data Gathering Approach; (4) Review Case Studies; (5) Develop Tailorable SE Framework for Technology Development and Transition; and (6) Validate Framework.The framework allows S&T project leaders and engineers to customize a recommended set of SE processes, methods and tools for their specific project type, size, maturity, budget, and integration level. Recommendations for SE methods are made at a summary level, with additional details available for desired activities. References to established SE documentation is also included for further investigation of appropriate SE techniques