Plasma Spectroscopy of Titanium Monoxide for Characterization of Laser Ablation

Ablation of titanium wafers in air is accomplished with 60 µs pulsed, 2.94 µm laser radiation. Titanium monoxide spectra are measured in the wavelength range of 500 nm to 750 nm, and molecular signatures include bands of the C3 Δ → X3 Δ α, B3 Π → X3 Δ γ\u27, and A3 Φ → X3 Δ γ transitions. The spatially and temporally averaged spectra appear to be in qualitative agreement with previous temporally resolved studies that employed shorter wavelengths and shorter pulse durations than utilized in this work. The background signals in the current study are possibly due to particulate content in the plume. A chemical kinetic model of the plume is being developed that will be coupled to a diatomic emission model in order to extract a molecular temperature from the observed spectra

Role of Excited State Photoionization in the 852.1 nm Cs Laser Pumped by Cs-Ar Photoassociation

Photoionization of Cs (6p 2P3/2) atoms during the operation of a Cs D2 line (852.1 nm: 6p 2P3/2→6s 2S1/2) laser, pumped by free→free transitions of thermal Cs-Ar ground state pairs, has been investigated experimentally and computationally. Photoexcitation of Cs vapor/Ar mixtures through the blue satellite of the D2 transition (peaking at 836.7 nm) selectively populates the 2P3/2 upper laser level by the dissociation of the CsAr excited complex. Comparison of laser output energy data, for instantaneous pump powers up to 3 MW, with the predictions of a numerical model sets an upper bound of 8 × 10−26 cm4 W−1 on the Cs (6p 2P3/2) two photon ionization cross-section at 836.7 nm which corresponds to a single photon cross-section of 2.4 × 10−19 cm2 for a peak pump intensity of 3 MW cm−2

Frozen Disorder in a Driven System

We investigate the effects of quenched disorder on the universal properties of a randomly driven Ising lattice gas. The Hamiltonian fixed point of the pure system becomes unstable in the presence of a quenched local bias, giving rise to a new fixed point which controls a novel universality class. We determine the associated scaling forms of correlation and response functions, quoting critical exponents to two-loop order in an expansion around the upper critical dimension d$_c=5$.Comment: 5 pages RevTex. Uses multicol.sty. Accepted for publication in PR

Density Functional for Anisotropic Fluids

We propose a density functional for anisotropic fluids of hard body particles. It interpolates between the well-established geometrically based Rosenfeld functional for hard spheres and the Onsager functional for elongated rods. We test the new approach by calculating the location of the the nematic-isotropic transition in systems of hard spherocylinders and hard ellipsoids. The results are compared with existing simulation data. Our functional predicts the location of the transition much more accurately than the Onsager functional, and almost as good as the theory by Parsons and Lee. We argue that it might be suited to study inhomogeneous systems.Comment: To appear in J. Physics: Condensed Matte

Unified Homogenization Theory for Magnetoinductive and Electromagnetic Waves in Split Ring Metamaterials

A unified homogenization procedure for split ring metamaterials taking into account time and spatial dispersion is introduced. The procedure is based on two coupled systems of equations. The first one comes from an approximation of the metamaterial as a cubic arrangement of coupled LC circuits, giving the relation between currents and local magnetic field. The second equation comes from macroscopic Maxwell equations, and gives the relation between the macroscopic magnetic field and the average magnetization of the metamaterial. It is shown that electromagnetic and magnetoinductive waves propagating in the metamaterial are obtained from this analysis. Therefore, the proposed time and spatially dispersive permeability accounts for the characterization of the complete spectrum of waves of the metamaterial. Finally, it is shown that the proposed theory is in good quantitative and qualitative agreement with full wave simulations.Comment: 4 pages, 3 figure

Assessing Physical Activity in People With Mental Illness: 23-country Reliability and Validity of the Simple Physical Activity Questionnaire (SIMPAQ)

Background: Physical inactivity is a key contributor to the global burden of disease and disproportionately impacts the wellbeing of people experiencing mental illness. Increases in physical activity are associated with improvements in symptoms of mental illness and reduction in cardiometabolic risk. Reliable and valid clinical tools that assess physical activity would improve evaluation of intervention studies that aim to increase physical activity and reduce sedentary behaviour in people living with mental illness. Methods: The five-item Simple Physical Activity Questionnaire (SIMPAQ) was developed by a multidisciplinary, international working group as a clinical tool to assess physical activity and sedentary behaviour in people living with mental illness. Patients with a DSM or ICD mental illness diagnoses were recruited and completed the SIMPAQ on two occasions, one week apart. Participants wore an Actigraph accelerometer and completed brief cognitive and clinical assessments. Results: Evidence of SIMPAQ validity was assessed against accelerometer-derived measures of physical activity. Data were obtained from 1010 participants. The SIMPAQ had good test-retest reliability. Correlations for moderate-vigorous physical activity was comparable to studies conducted in general population samples. Evidence of validity for the sedentary behaviour item was poor. An alternative method to calculate sedentary behaviour had stronger evidence of validity. This alternative method is recommended for use in future studies employing the SIMPAQ. Conclusions: The SIMPAQ is a brief measure of physical activity and sedentary behaviour that can be reliably and validly administered by health professionals.Universidad Pablo de Olavide de Sevilla. Departamento de Deporte e Informátic

PREDISSOCIATIVE RATE CONSTANTS FOR Bi2(A)Bi_{2}(A) FROM PULSED DYE LASER LIFETIME DATA

Author Institution: DEPARTMENT OF ENGINEERING PHYSICS, AIR FORCE INSTITUTE OF TECHNOLOGYA pulsed dye laser apparatus was used to obtain lifetime data for $Bi_{2}(A0^{+}_{u} \rightarrow X^{1}\Sigma^{+}_{g})$ transitions. The collision free lifetimes for $v^{\prime}=20$ to $v^{\prime}=39$, and $J \leq 105$, were investigated for effects of heterogeneous predissociation. The observed predissociation rates, establish $k_{pd,v^{\prime}} = 153$ 1/sec to $1.5 \times 10^{5} 1/sec$ for $v^{\prime}=21$ to 39. Rapid predissociation and the dense $Bi_{2}(A \rightarrow X)$ spectrum require both traditional lifetime measurements and synthetic spectrum to determine the full range of observed rates

LASER EXCITATION SPECTRA AND FRANK-CONDON FACTORS FOR Bi2X1Σg+→A0u+Bi_{2} X^{1} \Sigma^{+}_{g} \rightarrow A 0^{+}_{u}

Author Institution: PHILLIPS LABORATORY, KIRTLAND AIR FORCE BASE; DEPARTMENT OF ENGINEERING PHYSICS, AIR FORCE INSTITUTE OF TECHNOLOGYLaser excitation spectra of the lowest vibrational levels, $v^{\prime \prime}=2-5$ and $v^{\prime}=0-4$, for the $Bi_{2}X^{1} \Sigma^{+}_{g} \rightarrow A 0^{+}_{u}$ system have been recorded for a wide range of rotational levels, $0 < J < 211$, at Doppler-limited resolution of $0.013 cm^{-1}$. New rotational term values and spectroscopic constants are reported, improving the accuracy of predicted line positions for high rotational levels by as much as $0.8 cm^{-1}$. In addition, Frank-Condon factors are computed and compared with experimental observations from CW laser-induced fluorescence spectra

SPECTROSCOPY OF THE ν1+ν2−ν3,2ν1−ν3,2ν1,3ν1,2ν1+ν3\nu_{1} + \nu_{2} - \nu_{3}, 2\nu_{1} - \nu_{3}, 2\nu_{1}, 3\nu_{1}, 2\nu_{1} + \nu_{3} AND 3ν1+ν33\nu_{1} + \nu_{3} OVERTONE AND COMBINATION BANDS OF BrNO

Author Institution: Air Force Research Laboratory; Department of Engineering Physics, Air Force Institute of TechnologyThe rotation structure of the $\nu_{1} + \nu_{2} - \nu_{3}, 2\nu_{1} - \nu_{3}, 2\nu_{1}, 3\nu_{1}, 2\nu_{1} + \nu_{3}$ and $3\nu_{1} + \nu_{3}$s overtone and combination bands of BrNO were examined at high resolution $(.005-.01 cm^{-1})$ using Fourier Transform Spectroscopy. Over 4900 spectral lines were recorded for the two isotopomers $^{79}BrNO$ and $^{81}BrNO$. The rotational and quartic distortion terms, inertia defects and asymmetry parameters were determined for the (200), (300), (001), (200), (301) and (110) vibrational levels. The first-order vibration-rotation interaction terms were also determined

WAVELENGTH. RESOLVED FLUORESCENCE STUDIES OF THE COLLISION DYNAMICS OF Br2Br_{2} (B)

$^{1}$ L.J. van de Burgt and M. C. Heaven, Chem. Phys. 103. 407 (1986)Author Institution: Department of Chemistry, Emory University; AFWL, Kirtland AFBContinuous wave excitation and wavelength-resolved fluorescence techniques have been used to study the self-quenching and energy transfer kinetics of $Br_{2} (B)$. A self-quenching rate of $4\times 10^{-10} cm^{3} molecule^{-1} s^{-1}$ was observed for the levels with $v>10, J^{\prime}>15$, in excellent agreement with the results from pulsed $measurements.^{1}$ The rate constants for rotational energy transfer (summed over all final states) were found to be around $6\times 10^{-11} cm^{3} molecule^{-1} S^{-1}$. An upper bound of $5\times 10^{-12} cm^{3} molecule^{-1} S^{-1}$ was established for the vibrational energy transfer rate constant. The c.w. measurements are at variance with the energy transfer rate constants obtained from models of the time-resolved fluorescence decay kinetics.1 The reason for these discrepancies will be discussed