Yutaka Matsumi

Bio: Yutaka Matsumi is an academic researcher from Nagoya University. The author has contributed to research in topics: Photodissociation & Laser-induced fluorescence. The author has an hindex of 37, co-authored 215 publications receiving 4730 citations. Previous affiliations of Yutaka Matsumi include Hokkaido University & University of Southern Denmark.

Fine structure branching ratios of the O(3Pj) atomic fragments from photodissociation of oxygen molecules at 157 and 193 nm

Abstract: Direct photodissociation and predissociation of molecular oxygen from the B 3∑−u state have been studied by photoexcitation at 157 and 193 nm, respectively. The fine structure branching ratios and Doppler profiles of O(3Pj) photofragments were measured by a resonance‐enhanced multiphoton ionization technique. The branching ratios of O(3Pj) j=2,1,0 are 0.74 ±0.03: 0.21 ±0.02: 0.042±0.004 for photodissociation at 157 nm and 0.47±0.05: 0.31 ±0.04: 0.22±0.44 at 193 nm. Both distributions are not statistical. The Doppler profiles of O(3Pj) from photodissociation of O2 at 157 nm are consistent with formation of O(1D)+O(3Pj).

Doppler spectroscopy of hydrogen and chlorine atoms from photodissociation of silane, germane, chlorosilanes, and chloromethanes in the vacuum ultraviolet region

Abstract: Silane, germane, chlorosilanes, and chloromethanes are photodissociated at 157.6 nm. SiH 4 and GeH 4 are also photodissociated by a two-photon process at 243.1 nm. Hydrogen and chlorine atoms are detected using multiphoton ionization technique for measurement of Doppler profiles. The kinetic energy distribution of the nascent hydrogen atoms from silane and germane are derived from the Doppler profiles, which are Boltzmann

MegaSense: Feasibility of Low-Cost Sensors for Pollution Hot-spot Detection

Abstract: Air pollution is a major problem in urban areas, where high population density is accompanied with excess anthropomorphic emissions impacting the environment and increasing health effects. Highly accurate air quality monitoring stations have been used to monitor the severity of the problem and warn citizens. However, air quality can vary sharply even within the same city block, and pollution exposure can vary even 30% between individuals living in the same residence. Therefore, a dense deployment of air quality sensors is needed to detect these variations, and protect citizens from overexposure. Low-cost air quality sensors make it possible to densely instrument a city and detect hot spots as they happen. However, thus far limited information exists on their accuracy and practicability. In this paper, we conduct a 44-day measurement campaign to assess performance of low-cost air quality monitors under different environmental conditions. As practical use case, we consider pollution hot spot detection. Our results show that the mean error of low-cost sensors is small, but the variation in error is significantly larger than with reference sensors. We also show that the accuracy is sufficient for applications relying on variations in air quality index values, such as hot spot detection.

Vibrational and rotational energy distribution of ClO produced in reactions of O(1D) atoms with HCl, CCl4, and chlorofluoromethanes

Abstract: Nascent state‐resolved ClO(X 2Π) radicals produced in reactions of O(1D) with HCl, CCl4, CFCl3, CF2Cl2, and CF3Cl have been measured, using vacuum‐ultraviolet laser‐induced fluorescence of the ClO(C 2Σ−–X 2Π) transition. Rotational temperatures of ClO (X 2Π3/2, v=0 and 1) are 900–1000 K for chlorofluoromethanes and 2050±60 K (v=0) and 1770±180 K (v=1) for HCl. The rotational distribution for the O(1D)+HCl system is interpreted by the orbital‐to‐rotational angular momentum transfer mechanism. Vibrational level populations of the ClO(v=0–3) products are inverted for CCl4 and chlorofluoromethanes, but not for HCl. Vibrational excitations in the v=0–3 levels are higher for the reactions with the larger available energies.

Doppler spectroscopy of hydrogen atoms from the photodissociation of saturated hydrocarbons and methyl halides at 157 nm

Abstract: Hydrocarbons (CnH2n+2, n=3, 4, and 6) and methyl halides (CH3X, X=Cl, Br, I) are photodissociated at 157 nm. The hydrogen atom photofragments are detected by a resonance‐enhanced multiphoton ionization technique. The Doppler profiles of the hydrogen atoms from hydrocarbons are well represented by a Gaussian profile, while those from methyl halides by a mixture of a Gaussian and a non‐Gaussian profiles. These Doppler profiles are interpreted assuming that (a) hot ethyl photofragments from hydrocarbons result in the formation of hydrogen atoms and (b) methyl halides undergo both direct and indirect photolytic scissions of the C—H bonds at 157 nm.

Velocity map imaging of ions and electrons using electrostatic lenses: Application in photoelectron and photofragment ion imaging of molecular oxygen

Abstract: The application of electrostatic lenses is demonstrated to give a substantial improvement of the two-dimensional (2D) ion/electron imaging technique. This combination of ion lens optics and 2D detection makes “velocity map imaging” possible, i.e., all particles with the same initial velocity vector are mapped onto the same point on the detector. Whereas the more common application of grid electrodes leads to transmission reduction, severe trajectory deflections and blurring due to the non-point source geometry, these problems are avoided with open lens electrodes. A three-plate assembly with aperture electrodes has been tested and its properties are compared with those of grid electrodes. The photodissociation processes occurring in molecular oxygen following the two-photon 3dπ(3Σ1g −)(v=2, N=2)←X(3Σg −) Rydberg excitation around 225 nm are presented here to show the improvement in spatial resolution in the ion and electron images. Simulated trajectory calculations show good agreement with experiment and ...

Perfluoroalkyl and polyfluoroalkyl substances in the environment: Terminology, classification, and origins

Abstract: The primary aim of this article is to provide an overview of perfluoroalkyl and polyfluoroalkyl substances (PFASs) detected in the environment, wildlife, and humans, and recommend clear, specific, and descriptive terminology, names, and acronyms for PFASs. The overarching objective is to unify and harmonize communication on PFASs by offering terminology for use by the global scientific, regulatory, and industrial communities. A particular emphasis is placed on long-chain perfluoroalkyl acids, substances related to the long-chain perfluoroalkyl acids, and substances intended as alternatives to the use of the long-chain perfluoroalkyl acids or their precursors. First, we define PFASs, classify them into various families, and recommend a pragmatic set of common names and acronyms for both the families and their individual members. Terminology related to fluorinated polymers is an important aspect of our classification. Second, we provide a brief description of the 2 main production processes, electrochemical fluorination and telomerization, used for introducing perfluoroalkyl moieties into organic compounds, and we specify the types of byproducts (isomers and homologues) likely to arise in these processes. Third, we show how the principal families of PFASs are interrelated as industrial, environmental, or metabolic precursors or transformation products of one another. We pay particular attention to those PFASs that have the potential to be converted, by abiotic or biotic environmental processes or by human metabolism, into long-chain perfluoroalkyl carboxylic or sulfonic acids, which are currently the focus of regulatory action. The Supplemental Data lists 42 families and subfamilies of PFASs and 268 selected individual compounds, providing recommended names and acronyms, and structural formulas, as well as Chemical Abstracts Service registry numbers. Integr Environ Assess Manag 2011;7:513–541. © 2011 SETAC

Couplings between changes in the climate system and biogeochemistry

Abstract: Couplings Between Changes in the Climate System and Biogeochemistry Coordinating Lead Authors: Kenneth L. Denman (Canada), Guy Brasseur (USA, Germany) Lead Authors: Amnat Chidthaisong (Thailand), Philippe Ciais (France), Peter M. Cox (UK), Robert E. Dickinson (USA), Didier Hauglustaine (France), Christoph Heinze (Norway, Germany), Elisabeth Holland (USA), Daniel Jacob (USA, France), Ulrike Lohmann (Switzerland), Srikanthan Ramachandran (India), Pedro Leite da Silva Dias (Brazil), Steven C. Wofsy (USA), Xiaoye Zhang (China) Contributing Authors: D. Archer (USA), V. Arora (Canada), J. Austin (USA), D. Baker (USA), J.A. Berry (USA), R. Betts (UK), G. Bonan (USA), P. Bousquet (France), J. Canadell (Australia), J. Christian (Canada), D.A. Clark (USA), M. Dameris (Germany), F. Dentener (EU), D. Easterling (USA), V. Eyring (Germany), J. Feichter (Germany), P. Friedlingstein (France, Belgium), I. Fung (USA), S. Fuzzi (Italy), S. Gong (Canada), N. Gruber (USA, Switzerland), A. Guenther (USA), K. Gurney (USA), A. Henderson-Sellers (Switzerland), J. House (UK), A. Jones (UK), C. Jones (UK), B. Karcher (Germany), M. Kawamiya (Japan), K. Lassey (New Zealand), C. Le Quere (UK, France, Canada), C. Leck (Sweden), J. Lee-Taylor (USA, UK), Y. Malhi (UK), K. Masarie (USA), G. McFiggans (UK), S. Menon (USA), J.B. Miller (USA), P. Peylin (France), A. Pitman (Australia), J. Quaas (Germany), M. Raupach (Australia), P. Rayner (France), G. Rehder (Germany), U. Riebesell (Germany), C. Rodenbeck (Germany), L. Rotstayn (Australia), N. Roulet (Canada), C. Sabine (USA), M.G. Schultz (Germany), M. Schulz (France, Germany), S.E. Schwartz (USA), W. Steffen (Australia), D. Stevenson (UK), Y. Tian (USA, China), K.E. Trenberth (USA), T. Van Noije (Netherlands), O. Wild (Japan, UK), T. Zhang (USA, China), L. Zhou (USA, China) Review Editors: Kansri Boonpragob (Thailand), Martin Heimann (Germany, Switzerland), Mario Molina (USA, Mexico) This chapter should be cited as: Denman, K.L., G. Brasseur, A. Chidthaisong, P. Ciais, P.M. Cox, R.E. Dickinson, D. Hauglustaine, C. Heinze, E. Holland, D. Jacob, U. Lohmann, S Ramachandran, P.L. da Silva Dias, S.C. Wofsy and X. Zhang, 2007: Couplings Between Changes in the Climate System and Biogeochemistry. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.