Kentaro Misawa

Vibrational Signature of the Conformers in Tyramine Studied by IR Dip and Dispersed Fluorescence Spectroscopies

Dispersed fluorescence and IR dip spectra of seven conformers of tyramine were measured in a supersonic jet. Observed vibrational bands are assigned based on quantum chemical calculations. The vibrational frequency of out-of-plane CH bending in the benzene ring shows characteristic shifts according to the conformation of C(beta)-C(alpha), while that of CH stretching in the methylene chain reflects the conformation of N-C(beta). From these vibrational frequencies, assignments of the conformers observed in the S(1)-S(0) laser induced fluorescence spectrum are discussed.

Time-resolved measurements of low concentration aromatic hydrocarbons in diesel exhaust using a resonance enhanced multi-photon ionization method

Abstract Time-resolved measurements of the concentration of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) in exhaust from a diesel vehicle fitted with an oxidation catalyst and operated in JE05 mode are performed at a sensitivity of 10 ppb using a supersonic jet/resonance enhanced multi-photon ionization (Jet-REMPI) method. The concentrations of benzene, naphthalene, and phenol in exhaust from the test vehicle are measured before entering and after exiting from the oxidation catalyst. The total hydrocarbon (THC) is measured simultaneously using a constant volume sample (CVS) instrument fitted with a flame ionization detector (FID). Concentration changes of benzene, naphthalene and phenol are recorded at 1 s intervals and quantified using standard samples. Comparison of these signals with the real-time THC data shows that the time dependence of the individual species is almost the same as that of the THC before the oxidation catalyst but substantially different after.

Quantitative Determination of Composition of Particle Type by Morphology of Nanoparticles in Diesel Exhaust and Roadside Atmosphere

Particles were collected in diluted diesel exhaust under high-idle and high-torque operating conditions and from the air above roadsides. We analyzed particle morphology of particles that were 30, 50, 70, and 100 nm in electrical mobility diameter (Dm) by transmission electron microscope. We classified ten types of particles based on particle morphology and found that diesel exhaust particles (DEPs) of Dm=70 and 100 nm composed at least 14% and 58%, respectively, of atmospheric particles at each particle size. From the two-dimensional transmission electron microscope images, we derived three-dimensional morphological properties of the agglomerates and found that the numbers and diameters of the primary particles in the agglomerates were similar to those of DEPs at a given Dm. However, the active surface areas of the roadside atmospheric particles were systematically smaller than those of DEPs.

Analysis of Low-Lying Gerade Rydberg States of Acetylene Using Two-Photon Resonance Fluorescence Excitation Spectroscopy

The np gerade Rydberg states of acetylene were analyzed using two-photon resonance fluorescence excitation spectroscopy in the 72,000-93,000 cm(-1) energy region. The npπ(1)Σ(g)(+) and npπ(1)Δ(g) Rydberg series (n = 3-5) were identified in the fluorescence excitation spectrum measured by monitoring the C(2) d(3)Π(g)-a(3)Π(u) Swan system. Some vibronic bands were assigned to the npπ(1)Δ(g)-X̃(1)Σ(g)(+) transition on the basis of rotational analysis. The 5pσ(1)Π(g) state was observed, which is the first such observation in an npσ(1)Π(g) series. Rotational analysis of the 5pσ(1)Π(g)-X̃(1)Σ(g)(+) transition showed e/f-symmetry dependent predissociation of acetylene in the 5pσ(1)Π(g) state. The 0(0)(0) band of the deuterated acetylene (C(2)D(2)) 4pπ(1)Σ(g)(+)-X̃(1)Σ(g)(+) transition exhibits an atypical structure, which was satisfactorily reproduced by a simple model of quantum interference between the discrete and quasi-continuum states. The predissociative lifetimes of the npπgerade Rydberg states were estimated from the spectral profiles. The predissociation mechanism of acetylene in the Rydberg states is discussed.