Sumio Yamaguchi

Dissociative excitation of SiH4 by collisions with metastable argon atoms

Abstract The excitation transfer from Ar* to SiH 4 has been studied by observing UV and visible emission in a flowing afterglow and beam apparatus. The emission rates of Sill (A 2 Δ) and Si* atoms have been determined. From the nascent rovibrational distribution of SiH(A), the fractions of the available energy deposited into vibration and rotation of SiH(A) were estimated to be 2.9% and 4.4%, respectively.

The SiH+(A 1Π–X 1Σ+) emission produced from the thermal energy reaction of He+ with SiH4 under single collision conditions

A flowing afterglow reactor has been coupled to a low‐pressure chamber for an optical spectroscopic study of the charge–transfer reaction of He+ with SiH4 at thermal energy. The SiH+(Au20091Π–Xu20091Σ+) emission was observed in the 380–610 nm region. The nascent vibrational and rotational distributions of SiH+(A) have been determined. The vibrational distribution for 0≤v’≤3 was approximately exponential with an effective vibrational temperature of 820±60 K. The rotational temperature decreased from 600 K for v’=0 to 300 K for v’=3. These data indicated that only about 3% of the excess energy is released as internal energy of SiH+(A). From the emission rate constant, SiH+(A) represents about 25% of the total SiH+ ion in the He++SiH4 reaction.

Electronic excitation of the d 3Δi and a′ 3Σ+ states of carbon monoxide by metastable kr(3p2) atoms

Abstract Molecular CO emission resulting from the Kr(3P2) + CO reaction in the flowing afterglow indicates that a few near-resonant vibrational levels of the d 3Δi and a′ 3Σ + states are preferentially populated. The mechanism of excitation transfer is discussed in terms of energy resonance and Franck-Condon criteria.

The a-X transition of GeH+

Etude des systemes GeH + (a-X) dans le visible. 5 nouvelles bandes sont observees et utilisees pour obtenir les constantes de vibration

Nascent rovibrational distribution of O+2(A 2Πu) produced by He(2 3S) Penning ionization of O2

The He(2u20093S) Penning ionization of O2 to give O+2(Au20092Πu) has been studied by observing the O+2(Au20092Πu–Xu20092Πg) emission in beam and flowing afterglow apparatus. A comparison of beam and flowing afterglow data indicates that the nascent rovibrational distribution is lost in the flowing afterglow due to collisional relaxation. The nascent vibrational distribution of O+2(Au20092Πu) shifts to lower vibrational levels in comparison with the Franck–Condon factors for vertical O2(X)→O+2(A) ionization. The rotational temperature decreases from 4200 K for v’=0 to 400 K for v’=13. Vibrational relaxation of O+2(A) accompanied by a significant rotational excitation is explained as a result of a short‐range repulsive interaction [He–O+2(A)→He+O+2(A)] in the exit channel.

Nascent vibrational and rotational distributions of CH+ (A 1Π) produced from the charge transfer reaction of He+ with C2H2 at thermal energy

The CH+(Au20091Π−Xu20091Σ+) emission has been observed from the He++C2H2 reaction at thermal energy under low pressure conditions. The nascent vibrational distribution for v′=0−3 was nearly exponential with a Boltzmann temperature of 2300±300 K. The nascent rotational temperature varied from 3000±500 K for v′=0 to 2000±1000 K for v′=3. The fractions of the available energy deposited into rotation 〈fr〉 and vibration 〈u2009fv〉 were evaluated to be 21% and 9%, respectively.

Observation of the BBr+ emission spectrum: vibrational analysis of the A2Π12 − X2Σ+ system

Abstract A new visible emission system has been observed from the flowing afterglow reactions of BBr3 in the 470-515 nm region. It was assigned to the A2Πr − X2Σ+ transition of BBr+ From the vibrational analysis, the following spectroscopic constants of the A 2Π 1 2 and X2Σ+ states for 11BBr+ have been estimated (in cm−1): Te = 20171, ωe = 813.8, ωexe = 7.5, ωe = 761.5, and ωexe = 6.3.

The a3Π0+,1-X1Σ+ emission systems of SnH+

Abstract New visible emission systems have been observed from the helium afterglow reaction of SnH 4 . On the basis of the rotational analysis, they were interpreted as the a 3 Π 0 − -X 1 Σ + and a 3 Π 1 -X 1 Σ + subsystems of SnH + . Spectroscopic constants have been obtained for the a 3 Π 0 + and X 1 Σ + states.

Nascent rovibrational distributions of OH+ and OD+ in the A 3Πi state produced from the dissociative charge transfer reactions of He+ with H2O and D2O at thermal energy

The thermal‐energy charge transfer reaction of He+ with H2O(D2O) has been investigated by observing the Au20093Πi–Xu20093Σ− emission of OH+(OD+) at low pressures (<3 mTorr). The vibrational distributions in Au20093Πi of OH+(OD+) are 0.66(0.55)v’=0, 0.20(0.26)v’=1, 0.10(0.13)v’=2, and 0.04(0.06)v’=3. The rotational distributions for v’=0–3 of OH+(OD+) are expressed by a single Boltzmann temperature of 1700±200 (1800±200) K. The fractions of the available energy deposited into rotation 〈u2009fr〉 and vibration 〈u2009fv〉 for OH+(OD+) are evaluated to be 4.9(5.5)% and 3.9(4.1)%, respectively, indicating that a large amount of the available energy is partitioned into the relative translational energy.

Dissociative excitation of SiH4 by collisions with krypton active species

Abstract The dissociative excitation of SiH 4 by collisions with metastable Kr( 3 P 2 ) atoms and (Kr + ) * ions has been studied using flowing afterglow and beam apparatus. The emission rate constants of SiH(A 2 Δ) and Si * produced from the Kr( 3 P 2 )/SiH 4 reaction were determined to be (1.0±0.3)×10 −11 and (0.0069±0.0021)×10 −11 cm 3 s −1 , respectively. The nascent rovibrational distribution of SiH(A) was estimated from a spectral simulation: N 0 : N 1 : N 2 = 100 ( T 0 = 1400 K):40 ( T 1 = 1100 K):5 ( T 2 = 800 K). When (Kr + ) * ions were involved in the discharge flow, strong Si * lines resulting from electron-ion recombination processes were observed.