Katsuyoshi Yamasaki - Academia.edu (original) (raw)

Papers by Katsuyoshi Yamasaki

The Journal of Physical Chemistry A

Chemical Physics Letters, 2019

Atomic sulfur S(3p 4 3 P 2) was excited to the 3p 4 4p 3 P 2 state by two-photon absorption. • Th... more Atomic sulfur S(3p 4 3 P 2) was excited to the 3p 4 4p 3 P 2 state by two-photon absorption. • The lifetimes of S(3p 4 4p 3 P J) were measured by the emission from the 3p 3 4s 3 S state. • The rate coefficient for overall quenching of S(3p 4 4p 3 P J) by He has been determined. • The rate coefficient for quenching 3p 4 4p 3 P J → 3p 3 4s 3 S by He has been determined. • The branching ratio of the state-specific quenching 3p 4 4p 3 P J → 3p 3 4s 3 S is about 24%.

電磁気学の理解において意外に高い障壁がその単位系の理解である。単位はそもそも人間が共通の"言葉"で量の大きさを伝達し合うために考案したものであるが、電磁気現象の記述において多... more 電磁気学の理解において意外に高い障壁がその単位系の理解である。単位はそもそも人間が共通の"言葉"で量の大きさを伝達し合うために考案したものであるが、電磁気現象の記述において多くの単位(系)が存在するためにかえって混乱を導き、現象の定式化そのものよりも、単位系という人為的な約束ごとの理解にエネルギーを使わざるを得ないという本末転倒ともいえる状態に陥ることが多い。地球上には膨大な数の言語が存在するが、英語を"共通語"と認識することで、混乱が避けられている。電磁気学にもMKSA系という"標準語"が存在するが、分野によっては"昔の標準語"である別の単位系が依然として使われている(新刊書でも、分野によってはごく自然に使われているものもある)。名著あるいは古典と呼ばれる成書をひもといて、基本的な事項を勉強しようとすると、多くの場合、式の形や単位系が自分の(最新のSI単位系で)受けた教育における単位系と異なるために混乱してしまうことになる。単位系をきちんと理解しなければ、ある式にいろいろな物理量の値を代入して計算することもできなくなる。あるいは、ある単位系で書かれた式を別の単位系の式として変換するためにも単位系の理解は必須である。本書は、(特に電磁気学)単位系を自由に行き来できるような"ワザ"を習得するために書かれたmonographである。第10版第3

Chemical Physics Letters, 2022

Chemistry & Education, 2013

Chemical Physics Letters, 2021

Abstract Disulfur S 2 X 3 Σ g - was generated by irradiation of the pulsed laser light at 248 nm ... more Abstract Disulfur S 2 X 3 Σ g - was generated by irradiation of the pulsed laser light at 248 nm to the gaseous OCS. Single vibrational level of S 2 X 3 Σ g - , v = 0 - 4 was detected with laser-induced fluorescence (LIF) via the B 3 Σ u - − X 3 Σ g - transition. The kinetic analysis of the time-resolved LIF intensities recorded at varying pressures of CF4 has given the rate coefficients kv for vibrational relaxation of S 2 X 3 Σ g - , v to be kv/10−12 cm3 molecule−1 s−1 = 0.25 ± 0.07, 0.63 ± 0.06, and 1.2 ± 0.2 for v = 1, 2, and 3, respectively. The analysis also determined the relative detectabilities of the adjacent vibrational levels, deriving the nascent relative vibrational populations of the levels v = 0/1/2/3 to be 1/0.69 ± 0.05/0.47 ± 0.06/0.49 ± 0.07.

Journal of Molecular Spectroscopy, 2021

Abstract The highly rotationally excited states in the A 2 Σ + - X 2 Π Ω band of NO were investig... more Abstract The highly rotationally excited states in the A 2 Σ + - X 2 Π Ω band of NO were investigated by laser-induced fluorescence and multi-photon ionization spectroscopy. The rotational states with J up to 80.5 were prepared by CH3ONO photodissociation in the S1 and S2 excited states for spectroscopic measurements. In total, 3890 lines of nine vibronic bands were analyzed. The observed line positions deviated from the values calculated using the previous molecular constants as J increased in the J > 50.5 region. The sextet-order centrifugal distortion constants were determined for the A 2 Σ + and X 2 Π Ω states so that the transition frequencies associated with the high-J states could reproduce the observed results within the experimental accuracy. The band origin values, whose errors have been discussed in previous studies, were refined in the present analysis. The experimental condition to suppress the rotational relaxation of the high-J states was examined, enabling us to determine the higher-order centrifugal distortion constants.

The photodissociation dynamics of the heteroleptic Co(CO)3NO complex were investigated in the met... more The photodissociation dynamics of the heteroleptic Co(CO)3NO complex were investigated in the metal-to-carbonyl (CO) ligand charge-transfer band to compare the reactivity of the CO and nitrosyl (NO) ligands. The final state distributions of both the CO and NO fragments were measured using resonance-enhanced multiphoton ionization (REMPI) spectroscopy and velocity-map ion-imaging. The primary CO photofragment was differentiated from the secondary fragments of the subsequent unimolecular decomposition of coordinatively unsaturated intermediates by comparing the momentum distributions. The internal energy of the Co(CO)2NO intermediate was sufficiently high (≥348 kJ/mol) to be generated in the electronic excited state, indicating the occurrence of the primary CO elimination on an excited state. The NO fragments exhibited two velocity components. The analysis of the final state distributions suggested that the higher- and lower-kinetic-energy components originated from the direct primary elimination and sequential elimination, respectively. The direct photoelimination through a transiently bent ligand conformation was illustrated on the basis of a two-dimensional REMPI approach and time-dependent density functional theory calculations. The present results of both ligands demonstrate the correlation between elimination mechanisms and possible ligand conformations in the electronic excited state.

Chemical Physics Letters, 2018

Ultraviolet photodissociation dynamics of tricarbonylnitrosylcobalt, Co(CO) 3 NO, is studied by i... more Ultraviolet photodissociation dynamics of tricarbonylnitrosylcobalt, Co(CO) 3 NO, is studied by ionimaging. The photon energy is large enough to eliminate both NO and CO ligands in this heteroleptic complex, among which state-specific scattering is observed in the NO loss channel. The velocity distributions of the NO ligands exhibit clear evidence of two pathways. NO fragments with higher and lower kinetic energies are ascribed to direct dissociation in the electronic excited state and secondary decomposition following relaxation processes, respectively. The state-specific angular distribution of the faster component corroborates the rotational alignment, indicating the bent coordination of the nitrosyl ligand in the photoexcited state.

Chemical Physics Letters, 2016

Abstract Vibrationally excited S2(a1Δg, υ = 1–10) was generated by the S(1D) + OCS reaction and d... more Abstract Vibrationally excited S2(a1Δg, υ = 1–10) was generated by the S(1D) + OCS reaction and detected with dispersed laser-induced fluorescence (LIF) via the f1Δu–a1Δg transition. The time profiles of the vibrational levels of interest were recorded at varying pressures of He. A kinetic analysis made by the integrated profiles method has given the rate coefficients for vibrational relaxation of S2(a1Δg, υ = 1–9) by collisions with He. The energy gap law nicely correlates the probabilities of vibrational energy transfer per collision from S2(a1Δg), O 2 ( X 3 Σ g - ) , NO(X2Π), and CO(X1Σ+) to He.

The Journal of Physical Chemistry A, 2000

Collisional deactivation of OH(X 2 Π, V)1-4) by NH 3 has been studied using pulsed laser photolys... more Collisional deactivation of OH(X 2 Π, V)1-4) by NH 3 has been studied using pulsed laser photolysis coupled with the pulsed laser probe technique. Mixtures of O 3 /NH 3 /N 2 were photolyzed at 248 nm, and time-resolved OH populations were monitored via the ∆V) 0 and-3 sequences of the A 2 ∑ +-X 2 Π i transition. The following deactivation rate constants at 298 (1 K were obtained: (2.9 (0.2) × 10-11 for V) 1, (1.1 (0.2) × 10-10 for V) 2, (3.4 (0.4) × 10-10 for V) 3, and (4.1 (0.3) × 10-10 for V) 4 in units of cm 3 molecule-1 s-1 (the errors are 2σ). The present study is the first report on the rate constant for OH(V)4) + NH 3 reaction. The deactivation of OH(Ve3) by NH 3 can be elucidated by nonresonant V-V energy transfer caused by long-range interaction; that of V) 4 deviates from the gap law.

Chemical Physics Letters, 2015

Review of Scientific Instruments, 1995

An inexpensive gated integrator is made entirely of parts available in an ordinary electronics sh... more An inexpensive gated integrator is made entirely of parts available in an ordinary electronics shop. It works well to average the repetitive signals in observing the spectra of laser‐induced fluorescence, multiphoton ionization, and so on. The minimum gate delay of 200 ns and ...

The Journal of Physical Chemistry A, 2002

Nascent vibrational distributions of NH 2 (X 2 B 1 , V 2 ′′) 0-4) generated in the 193 nm photoly... more Nascent vibrational distributions of NH 2 (X 2 B 1 , V 2 ′′) 0-4) generated in the 193 nm photolysis of NH 3 at 298 (1 K have been determined by simple kinetic analysis. The vibrational levels of NH 2 (X 2 B 1) were detected by laser-induced fluorescence (LIF) excited via the Ã 2 A 1-X 2 B 1 system, and time-resolved concentration profiles were recorded. Rate constants for intramode relaxation of ν 2 vibration (V 2 ′′ f V 2 ′′-1) by collisions of He have been determined to be (4.2 (1.0) × 10-14 , (7.5 (0.5) × 10-14 , (1.6 (0.1) × 10-13 , (3.0 (0.1) × 10-13 in units of cm 3 molecule-1 s-1 for V 2 ′′) 1, 2, 3, and 4, respectively. The quoted errors are 2σ. Rate constants for intermode coupling between V 1 ′′) 1 and V 2 ′′) 2 by He have also been determined to be (4.7 (1.6) × 10-12 (V 1 ′′)1 f V 2 ′′) 2) and (1.3 (0.4) × 10-12 cm 3 molecule-1 s-1 (V 1 ′′)1 r V 2 ′′) 2). Relative detectivities of the levels V 2 ′′) 1-4 were obtained by the kinetic analysis, and vibrational distributions immediately after the photolysis have been given to be 2.2 (0.7/1.0/ < 1.3/0.66 (0.3/ < 3.0 for V 2 ′′) 0/1/2/3/4 (normalized by the population of V 2 ′′) 1). To the best of our knowledge, this is the first quantitative report on the initial vibrational populations of NH 2 generated in the photolysis at 193 nm.

Laser Chemistry, 1995

The overall rate constant for the reaction NH(a1Δ ) + HN3 has been determined by the laser photol... more The overall rate constant for the reaction NH(a1Δ ) + HN3 has been determined by the laser photolysis of hydrogen azide (HN3) at 266 nm and 193nm. The visible emission from vibronically excited NH2(A˜2A1) was dispersed and its time-dependent profiles were measured at several wavelengths. The rate constants are dependent not only on the photolysis wavelengths but also on the vibrational levels of the NH2(A˜2A1) produced in the reaction. The intermolecular potential between NH(a1Δ) and HN3 was determined to be the form V(R) = –C/Rs (2 < s < 4, C: constant) from the analysis with a long-range potential approximation. The interaction between NH(a1Δ ) and HN3 is mainly governed by the dipoledipole interaction in the initial stage of the reaction.

Journal of Theoretical and Computational Chemistry, 2005

To elucidate the ionization dynamics, in particular the vibrational distribution, of H 2 O +(Ã) p... more To elucidate the ionization dynamics, in particular the vibrational distribution, of H 2 O +(Ã) produced by photoionization and the Penning ionization of H 2 O and D 2 O with He *(2 3S) atoms, Franck–Condon factors (FCFs) were given for the [Formula: see text] ionization, and the transition probabilities were presented for the [Formula: see text] emission. The FCFs were obtained by quantum vibrational calculations using the three-dimensional potential energy surfaces (PESs) of [Formula: see text] and [Formula: see text] electronic states. The global PESs were determined by the multi-reference configuration interaction calculations with the Davidson correction and the interpolant moving least squares method combined with the Shepard interpolation. The obtained FCFs exhibit that the [Formula: see text] state primarily populates the vibrational ground state, as its equilibrium geometry is almost equal to that of [Formula: see text], while the bending mode (ν2) is strongly enhanced for ...

The Journal of Chemical Physics, 1989

State‐specific total quenching rate constants are measured for selected rotational levels of Br u... more State‐specific total quenching rate constants are measured for selected rotational levels of Br under single collision conditions with argon at 296 K. A strict criterion is used to obtain single collision conditions in a cell experiment. A 0.04 cm bandwidth, etalon‐narrowed pulsed ...

Chemical Physics Letters, 2011

We calculated ionization potentials (IPs) to create single core-hole states and double ionization... more We calculated ionization potentials (IPs) to create single core-hole states and double ionization potentials (DIPs) to create double core-hole (DCH) states for a series of trihalosilyl-trimethylsilyl molecules bridged with hydrocarbons. From the calculated DIPs, IPs, and the hole-hole repulsion energies, we extracted the excess relaxation energies for the creation of DCHs at a single atomic site and interatomic relaxation energies for the creation of DCHs at two different sites. These excess and interatomic relaxation energies depend solely on the chemical environment around the atom(s) with core hole(s). We found that the interatomic relaxation is almost blocked by a dimethylene group (-CH2CH2-).