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We report the results of an evaluation of laser-induced breakdown spectroscopy (LIBS) for the detection of candidate halon replacement compounds (CF 4 , CF 3 H, CF 2 H 2 , C 2 F 5 H). The fundamental (1.064 µm) from a Nd: YAG Q-switched pulsed laser was focused into an air flow containing 0.0005-5% of the analyte halocarbon compounds. The laser-produced plasma emission consists of a large number of intense fluorine atom lines in the 600-850 nm spectral range. Limit-of-detection studies indicate that LIBS can detect these compounds in the parts per million range. Also, we have recorded singleshot LIBS spectra with good signal-to-noise ratios using an intensified photodiode array. Our results indicate that LIBS is a promising detection technique for in situ and real-time measurement of halons during use in full-scale fire suppression testing.

To investigate the effects of a geothermal area on the propagation of intermediate‐period (1–30 s) teleseismic body waves and surface waves, a specially designed portable seismograph system was operated in Yellowstone Caldera, Wyoming. Travel time residuals, relative to a station outside the caldera, of up to 2 s for compressional phases are in agreement with short‐period residuals for P phases measured by other investigators. Travel time delays for shear arrivals in the intermediate‐period band range from 2 to 9 s and decrease with increasing dT/dΔ. Measured Rayleigh wave phase velocities are extremely low, ranging from 3.2 km/s at 27‐s period to 2.0 km/s at 7‐s period; the estimated uncertainty associated with these values is 15%. We propose a model for compressional and shear velocities and Poisson's ratio beneath the Yellowstone caldera which fits the teleseismic body and surface wave data:it consists of a highly anomalous crust with an average shear velocity of 3.0 km/s overlying an upper mantle with average velocity of 4.1 km/s. The high average value of Poisson's ratio in the crust (0.34) suggests the presence of fluids there; Poisson's ratio in the mantle between 40 and approximately 200 km is more nearly normal (0.29) than in the crust. A discrepancy between normal values of Poisson's ratio in the crust calculated from short‐period data and high values calculated from teleseismic data can be resolved by postulating a viscoelastic crustal model with frequency‐dependent shear velocity and attenuation.

Laser-induced breakdown spectroscopy is evaluated as a means of detecting the fire suppressants CF(3)Br, C(3)F(7)H, and CF(4) and the refrigerant C(2)F(4)H(2). The feasibility of employing laser-induced breakdown spectroscopy for time- and space-resolved measurement of these agents during use, storage, and recharge is discussed. Data are presented that demonstrate the conditions necessary for optimal detection of these chemicals.

Photofragmentations, state interactions, and energetics of Rydberg and ion-pair states: Resonance enhanced multiphoton ionization via E and V (B) states of HCl and HBr J. Chem. Phys. 138, 044308 (2013); 10.1063/1.4776260 Two-dimensional resonance enhanced multiphoton ionization of H i Cl; i = 35, 37: State interactions, photofragmentations and energetics of high energy Rydberg states J. Chem. Phys. 134, 164302 (2011); 10.1063/1.3580876 Polarizationresolved (2+1) resonanceenhanced multiphoton ionization spectroscopy of CF3I (6s) Rydberg states J. Chem. Phys. 98, 4355 (1993); 10.1063/1.464997[3+2] resonance enhanced multiphoton ionization of I and Br formed from the infrared multiphoton decomposition of CF3I and CF3BrTime-of-flight mass spectrometry has been used to examine the spatial aniso.tropy and. . translational energy of 1+ and CFt fragments resulting from resonant multtphoton excttatIon of CF 31 in the 300-306 nm range. These ion species are shown to be largely the photofragments from the single-photon direct dissociation of CF 3 1+ generated via a new resonant (2 + 1) multi photon ionization (MPI) transition. ghotoelectron spectroscopy shows that most of the parent CF 3 1+ is produced in its ground X 2E3/2 state by the resonant MPI process .. All the observed 1+ is formed via this parent ion photodissociation, while the observed CFt IS formed via statistical decomposition of the parent as well as parent ion photodissociation. The present results are discussed in the context of the current understanding of alkyl halide photodynamics.