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ABSTRACT Exposures of occupants in school buses to on-road vehicle emissions, including emissions from the bus itself, can be substantially greater than those in outdoor settings. A dual tracer method [...]

We demonstrate the application of a commercially available widely tunable continuous-wave external cavity quantum cascade laser as a spectroscopic source for the simultaneous detection of multiple gases. We measured broad absorption features of benzene and toluene between 1012 and 1063 [cm.sup.-1] (9.88 and 9.41 [micro]m) at atmospheric pressure using an astigmatic Herriott multipass cell. Our results show experimental detection limits of 0.26 and 0.41 ppm for benzene and toluene, respectively, with a 100 m path length for these two gases. [c] 2010 Optical Society of America OCIS codes: 140.5965, 280.0280, 300.6260, 300.6340.

A temporal filtering technique, complementary to spectral filtering, has been developed for laser-induced fluorescence measurements. The filter is applicable in cases where the laser-induced interfering signals and the signal of interest have different temporal characteristics. For the interfering-signal discrimination a picosecond laser system along with a fast time-gated intensified CCD camera were used. In order to demonstrate and evaluate the temporal filtering concept two measurement situations were investigated; one where toluene fluorescence was discriminated from interfering luminescence of an aluminum surface, and in the other one Mie scattering signals from a water aerosol were filtered out from acetone fluorescence images. A mathematical model was developed to simulate and evaluate the temporal filter for a general measurement situation based on pulsed-laser excitation together with time-gated detection. Using system parameters measured with a streak camera, the model was validated for LIF imaging of acetone vapor inside a water aerosol. The results show that the temporal filter is capable of efficient suppression of interfering signal contributions. The photophysical properties of several species commonly studied by LIF in combustion research have been listed and discussed to provide guidelines for optimum use of the technique. OCIS codes: 120.1740, 120.2440, 280.1740, 280.2490, 290.2648, 300.2530.

Different concentrations of zinc phthalocyanines (Zn-Pc) in toluene solution are prepared and characterized in order to obtain best conditions for realizing the films in poly(methyl methacrylate) (PMMA). The findings reveal that comparison of linear and nonlinear absorption properties of the films and their Zn-Pc concentration in the PMMA matrix have shown that an enhancement of the nonlinear optical coefficient arises despite the evidence of the initial aggregation of molecules.

The rate constants for the reactions of OH radicals with benzene and toluene are measured directly by a shock tube/ pulsed laser-induced fluorescence imaging method at high temperatures. The direct measurements of the high-temperature rate constants for the reactions of OH radicals with benzene and toluene is extended up to 1740 and 1480 K, respectively, and are in good agreement with the previous measurements.

The replacement reaction between hydrophobized Ag nanoparticles and hydrophobized AuCl4- in toluene are examined in detail. Solvent and temperature are influential environmental factors that determine the structure and composition of nanoparticles formed by the replacement reaction.

Thermal lens spectrometry configuration is used for studying CdSe/ZnS core-shell quantum dots (QDs) suspended in toluene and tetrahydrofuran (THF) solvents. The special features of the configuration are used for measuring fluorescence quantum yield ([eta]) excitation spectrum as it has simplified the measurement procedure and has improved the accuracy.

A rapid optical beating Brillouin scattering spectroscopy is applied to observe the thermal phonon resonance and obtain the phonon phase velocity. The experimental results showed the phonon propagation to be confined space filled with liquid toluene.

Highly enhanced nonlinear absorption cross section values of [Cu.sub.60](>DPAF-[C.sub.2M]), [C.sub.60](>DPAF-[C.sub.9]) and [C.sub.60](>DPAF-[C.sub.10]) dyads are detected in the 2.0 ps region in toluene. They are correlated to a trend showing higher efficiency in light transmittance attenuation for the dyads.

The article provides evidence of the suitability of the tracer zero-length column method in observing molecular transport under conditions of anomalous, single-file diffusion. The center-of-gravity diffusion mechanism is observed in single-file systems of finite length.

The development of a novel and convenient orthogonal method for the synthesis of asymmetrically tri- and tetrasubstituted pyrazines starting from para-methoxybenzyl-protected 3,5-dichloro-2(1H)-pyrazinones is demonstrated. The key step in the sequence involves mild, one-step iodine-catalyzed methylation with concomitant aromatization of the generated thiopyrazinone.

A study was conducted to understand the role of phenyl radical in the growth of PAHs (polycyclic aromatic hydrocarbons), pyrolysis of toluene with and without benzene. The results showed that the PAC (phenyl addition/cylization) mechanism is efficient for the growth of PAHs without the triple fusing site, for which the HACA (hydrogen abstraction/[C.sub.2][H.sub.2] addition) step is inefficient, and produces PAHs with five-membered rings.

A study was conducted to determine the chemical compositions of secondary organic aerosol (SOA) in urban air produced by photoirradiation of the toluene/[N[O.sub.x]/air system. The major chemical components of the aerosol were found to be hemiacetal and peroxy hemiacetal oligomers and low-molecular-weight dicarboxylic acids.

New modes of [H.sub.2] and [PhSiH.sub.3] additions for an 'end-on-bridged' [[Ta(IV)].sub.2]([mu]-[[eta].sup.1]:[[eta].sup.1]-[N.sub.2]) complex and for the bis([mu]-nitrido) [[Ta(V)([mu]-N)].sub.2] product derived from facile N=N bond cleavage are developed. These modes exhibit dinitrogen activation at ambient temperatures.

The results of a series of experiments which probe the structure of liquid MBA and how it solvates a series of disparate solutes including methanol, dimethyl sulfoxide, cyclohexane, toluene, and nitrobenzene is reported.

The master equation modeling of the isomerization of toluene oxide is described by focusing on the formation of the cresols. It was found that photolysis with a high-energy light source is expected to give a high yield of the thermal distribution of cresol products while photolysis with a low-energy light source favors formation of the thermally disfavored ortho isomer.

In this study, the sorption and the diffusion of toluene in HZSM-5, modified by chemical liquid deposition of tetraethoxysilane (TEOS), is discussed by the frequency response method. This conclusion is well supported by the fact that the amount of toluene ,molecules accessing the sorption sites using also the sinusoidal channels increases after the modification , while the total update remains unaffected.

Refractive index dispersion formulas were derived from the experimental refractive index data at 20 degrees C for chloroform, toluene, benzene and carbon disulfide. The calculation of nonlinear optical measurements in the UV, visible, and near -IR wavelength range in these liquids and solutions were obtained.

The adsorption of toluene in basic zeolites X and Y with molecular mechanics and quantum chemical methods is investigated. The results indicate that the adsorption process of a single molecule in fully crystalline alkali X or Y zeolite does not itself give rise to the activation of toluene.

The UV/vis/NIR spectra of 10 kinds of dissolved in toluene and the molar absorption coefficients is determined for each absorption peak. The findings indicate that the oscillator strengths for the 986 and 1406 nm absorption are about 1 order of magnitude smaller and those of the 986 nm absorption vary appreciably as the degree of filling of the 4f orbital changes.