Transition probabilities in OH A 2 sigma + - X 2 pi i: Bands with v prime = 0 and 1, v double prime = 0 to 4

Experimental results for relative vibrational band transition probabilities for v prime = 0 and 1, and v double prime = 0 to 4 in the A-X electronic system of OH are presented. The measurements, part of a larger set involving v prime = 0 to 4 and v double prime = 0 to 6, were made using spectrally dispersed laser-induced fluorescence (LIF) in the burnt gases of a flame. These Einstein coefficients will be useful in dynamics experiments for quantitative LIF determinations of OH radical concentrations in high v double prime

Laser-induced fluorescence determination of temperatures in low pressure flames

Rensberger KJ, Jeffries JB, Copeland RA, Kohse-Höinghaus K, Wise ML, Crosley DR. Laser-induced fluorescence determination of temperatures in low pressure flames. Applied Optics. 1989;28(17):3556-3566.Spatially resolved temperatures in a variety of low pressure flames of hydrogen and hydrocarbons burning with oxygen and nitrous oxide are determined from OH, NH, CH, and CN laser-induced fluorescence rotational excitation spectra. Systematic errors arising from spectral bias, time delay, and temporal sampling gate of the fluorescence detector are considered. In addition, we evaluate the errors arising from the influences of the optical depth and the rotational level dependence of the fluorescence quantum yield for each radical. These systematic errors cannot be determined through goodness-of-fit criteria and they are much larger than the statistical precision of the measurement. The severity of these problems is different for each radical; careful attention to the experimental design details for each species is necessary to obtain accurate LIF temperature measurements

Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions

In situ measurements of HCl during plasma etching of poly-silicon using a diode laser absorption sensor

Tunable diode laser absorption spectroscopy is used to monitor hydrogen chloride (HCl) concentration in a commercial, high-density, low-pressure plasma reactor during plasma etching. A near-infrared diode laser is used to scan the P(4) transition in the first overtone of HCl near 1.79 µm to measure changes in HCl levels. A variety of HBr and Cl2 feedstock recipes are investigated at a process pressure of 10 mTorr as a function of rf power transformer coupled plasma, bias power and the total flow rate. Using 50 ms averaging and a signal modulation technique, we estimate a minimum detectivity of 4 × 10−6 in peak absorbance, which corresponds to an HCl number density of ∼2 × 1011 cm−3. The diode-laser based HCl sensor is sufficiently sensitive to detect small concentration variations and HCl concentration correlates with poly-Si etch rate for the conditions studied. These measurements demonstrate the feasibility of a real-time diode laser-based sensor for etch rate monitoring and the potential for process control.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49064/2/e30918.pd

Haul-Out Behavior of Harbor Seals (Phoca vitulina) in Hood Canal, Washington

The goal of this study was to model haul-out behavior of harbor seals (Phoca vitulina) in the Hood Canal region of Washington State with respect to changes in physiological, environmental, and temporal covariates. Previous research has provided a solid understanding of seal haul-out behavior. Here, we expand on that work using a generalized linear mixed model (GLMM) with temporal autocorrelation and a large dataset. Our dataset included behavioral haul-out records from archival and VHF radio tag deployments on 25 individual seals representing 61,430 seal hours. A novel application for increased computational efficiency allowed us to examine this large dataset with a GLMM that appropriately accounts for temporal autocorellation. We found significant relationships with the covariates hour of day, day of year, minutes from high tide and year. Additionally, there was a significant effect of the interaction term hour of day : day of year. This interaction term demonstrated that seals are more likely to haul out during nighttime hours in August and September, but then switch to predominantly daylight haul-out patterns in October and November. We attribute this change in behavior to an effect of human disturbance levels. This study also examined a unique ecological event to determine the role of increased killer whale (Orcinus orca) predation on haul-out behavior. In 2003 and 2005 these harbor seals were exposed to unprecedented levels of killer whale predation and results show an overall increase in haul-out probability after exposure to killer whales. The outcome of this study will be integral to understanding any changes in population abundance as a result of increased killer whale predation

Applied Combustion Diagnostics

Kohse-Höinghaus K, Jeffries JB, eds. Applied Combustion Diagnostics. Combustion. New York: Taylor and Francis; 2002

LASER-INDUCED FLUORESCENCE FROM THE B2Σ+B^{2}\Sigma^{+} AND B′2ΔB^{\prime}{^{2}}\Delta STATES OF THE SiCl RADICAL*

$^{\ast}$ Supported by Internal Research and Development funds of SRI InternationalAuthor Institution: Chemical Physics Laboratory, SRI InternationalLaser-induced fluorescence (LIF) is observed following excitation of ground state SiCl molecules to either the $B^{2}\Sigma^{+}$ or the $B^{\prime}{^{2}}\Delta$ excited electronic states. Pulsed frequency-doubled light from an excimer-pumped dye laser excites the radicals in the afterglow of a low-pressure microwave discharge in He with a trace of added $SiCl_{4}$. The fluorescence from v' - 0-3 of the $B^{2}\Sigma^{+}$ state and $v^{\prime} - 0-1$ of the $B^{\prime}{^{2}}\Delta$ state is dispersed with 2 nm resolution and the relative vibrational band strengths are measured for $v^{\prime\prime} \leq 10$ in $B^{2}\Sigma^{+} - X^{2}\Pi$ emission and $v^{\prime\prime} \leq 3$ in $B^{\prime}{^{2}}\Delta - X^{2}\Pi$ emission. From the temporal evolution of the LIF, the fluorescence lifetimes of the B and the B' state are found to be $\leq 25$ ns and $1.7 \pm 0.5 \mu s$, respectively. This large difference in the time behavior of the LIF allows the overlapped excitation spectra to be clearly separated with different time gates. Preliminary analysis of the helium pressure dependence of the fluorescence from the $B^{\prime}{^{2}}\Delta$ indicates a collisional removal rate of - $6 \times 10^{-11} cm^{3}s^{-1}$. The dispersed fluorescence from the $B^{\prime}{^{2}}\Delta, v^{\prime} - 0$ state reveals a significant relaxation pathway is electronic-to-electronic collisional energy transfer to $v^{\prime} - 0.2$ in $B^{2}\Sigma^{+}$. The large magnitude of the collisional removal rate of the $B^{\prime}$ state by He is very surprising and further investigations are currently underway

LASER-INDUCED FLUORESCENCE FROM THE A2Δ,B2Π,C2Σ+A^{2}\Delta, B^{2}\Pi, C^{2}\Sigma^{+} AND G2Σ−G^{2}\Sigma^{-} STATES OF THE NS RADICAL∗RADICAL^{\ast}

$^{\ast}$ Supported by the National Science Foundation, Grant No. CPE-80-17521. $^{1}$ Y. Matsumi, T. Munakata, and T. Kasuya, J. Phys. Chem. 88, 264 (1984).Author Institution: Chemical Physics Laboratory, SRI InternationalLaser-induced fluorescence has been observed from transitions between $A^{2}\Delta, B^{2}\Pi, C^{2}\Sigma^{+}$, and $G^{2}\Sigma^{-}$ and the $X^{2}\Pi$ ground state of the NS molecule. NS was monitored in a flow reactor downstream from a low pressure microwave discharge in $SF_{6}$ and $N_{2}$. Laser radiation tunable from 2.8.8-336.0 nm with bandwidth $0.3 cm^{-1}$ was produced by Raman shifting a frequency doubled dye Laser. Rotationally resolved fluorescence excitation spectra of $A^{2}\Delta. v'=0-1; B^{2}\Pi, v'=0-12$; and $C^{2}\Sigma^{+}, v^{\prime}=0$ been observed. Relative band emission strengths for 12 bands of $A^{2}\Delta, 232$ bands of $B^{2}\Pi$ and 6 bands of $C^{2}\Sigma^{+}$ have been measured and Franck-Condon overlap factors determined. Preliminary observations indicate collision-induced transitions occur between fine structure levels of $B^{2}\Pi$. Rapid collisional quenching of $B^{2}\Pi, v^{\prime}=12$ and $A^{2}\Delta v^{\prime}=0$ (but not $A^{2}\Delta v^{\prime}=1$ or $B^{2}\Pi v^{\prime}=1-11$) suggests collisional mixing with predissociative levels. Lifetime measurements for $B^{2}\Pi$ and the observed collisional quenching of $B^{2}\Pi, v^{\prime}=12$ are in agreement with the recent results of Matsumi $et at.^{1}

TRANSITION PROBABILITIES IN THE A-X SYSTEM OF OH FROM v′=3v'=3

This work was supported by the Basic Energy Sciences Division of the Department of Energy. $^{*}$ Also: Department of Chemistry, Stanford University, Stanford, California 94305Author Institution: Molecular Physics Laboratory, SRI InternationalMeasurements were made on the emission from the $v^{\prime}=3$ level of the $A^{2}\Sigma^{+}$ state of OH. Fluorescence scans were taken while exciting the 3-0 band with a tunable laser. The OH was generated in the burnt gases of a low pressure flame where collisions are infrequent enough that energy transfer does not complicate the spectra. Transition probabilities were obtained for $v^{\prime\prime}=0$ to $v^{\prime\prime}=5$. Values for the high vibrational levels of the $X^{2}\Pi_{i}$ state are important for determining the behavior of the electronic transition moment at large internuclear separation. LIF measurements are planned on the $v^{\prime}=2$ and 4 levels of the A state