scholarly journals Photodissociation branching ratios of 12C16O from 110 500 to 113 045 cm−1: first observation of the C(1S) channel

2021 ◽  
Vol 647 ◽  
pp. A127
Author(s):  
Lichang Guan ◽  
Pan Jiang ◽  
Guodong Zhang ◽  
Tonghui Yin ◽  
Min Cheng ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Energy Range ◽  
Vacuum Ultraviolet ◽  
Branching Ratio ◽  
Atomic Emission ◽  
Branching Ratios ◽  
Ion Imaging ◽  
Fractional Rate ◽  
Solar Photolysis ◽  
Photochemical Modelling

Carbon monoxide (CO) is one of the most abundant molecular species in comets. Its photodissociation by the solar radiation in the vacuum ultraviolet (VUV) region produces excited atomic fragments C(1D), C(1S), and O(1D), which radiate at characteristic wavelengths when they decay to lower states. The fractional rate constants for generating these fragments from CO photodissociation under the entire range of the solar radiation field are key input values in modelling the observed atomic emission intensities from comets. In this study, the branching ratios of the four lowest dissociation channels C(3P)+O(3P), C(1D)+O(3P), C(3P)+O(1D), and C(1S)+O(3P) of the 12C16O photodissociation are measured in the VUV energy range between the threshold of producing the C(1S)+O(3P) channel (~110 500 cm−1) and the ionisation energy (IE) of 12C16O (~113 045 cm−1). We measured these ratios using the VUV time-slice velocity-map ion imaging apparatus. We observe a number of high Rydberg states in the aforementioned energy range, with most of them mainly producing ground C(3P) and O(3P) atomic fragments, and only a few of them producing a significant amount of excited C(1D) or O(1D) fragments. We also observe the excited C(1S) fragment from CO photodissociation and measured its branching ratio for the first time. Based on the photodissociation branching ratios measured in the current and previous studies, we are able to estimate the relative percentages of the excited atomic fragments C(1D), C(1S), and O(1D) from the solar photolysis of 12C16O below its IE. We discuss the implications for the photochemical modelling of the CO-dominated comet C/2016 R2 (Pan-STARRS).

scholarly journals Photodissociation branching ratios of 13C16O and 12C18O in the vacuum ultraviolet region from 107 800 to 109 700 cm−1

2020 ◽  
Vol 637 ◽  
pp. A37 ◽  
Author(s):  
Xiaoping Chi ◽  
Pan Jiang ◽  
Qihe Zhu ◽  
Min Cheng ◽  
Hong Gao
Keyword(s):  
Vacuum Ultraviolet ◽  
Isotope Effects ◽  
Branching Ratio ◽  
Branching Ratios ◽  
Spectroscopic Studies ◽  
Ultraviolet Region ◽  
Velocity Map Imaging ◽  
Absorption Bands ◽  
Two Photon ◽  
O Isotope

In this study, we present C+ ion photofragment spectroscopic studies and photodissociation branching ratio measurements for two CO isotopologs, 13C16O and 12C18O, in the vacuum ultraviolet (VUV) region from 107 800 cm−1 (92.76 nm) to 109 700 cm−1 (91.16 nm) using a time-slice velocity-map imaging setup and a tunable VUV laser radiation source generated by the two-photon resonance-enhanced four-wave mixing technique. Several absorption bands of 12C16O in the above energy region are reinvestigated up to higher rotational levels compared with previous studies. The results are compared among 12C16O, 13C16O, and 12C18O on a state-by-state basis, and the photodissociation branching ratios for channels C(1D) + O(3P), and C(3P) + O(1D) are dramatically changed for most of the absorption bands due to the substitutions of 12C by 13C and 16O by 18O. The branching ratios of 13C16O and 12C18O are close to each other due to their similar reduced masses. The strong and selective isotope effects obtained here not only provide useful information for understanding the complicated predissociation dynamics of CO, but are also important for developing a comprehensive photochemical model for explaining the C and O isotope heterogeneities as observed in the Solar System.

scholarly journals Dynamics of the Reaction S(1D) + HD, H2, and D2: Isotopic Branching Ratios and Translational Energy Release

1994 ◽  
Vol 14 (4) ◽  
pp. 235-244 ◽  
Author(s):  
Yousuke Inagaki ◽  
Sayed Mohammed Shamsuddin ◽  
Yutaka Matsumi ◽  
Masahiro Kawasaki
Keyword(s):  
Energy Release ◽  
Collision Energy ◽  
Vacuum Ultraviolet ◽  
Branching Ratio ◽  
Branching Ratios ◽  
Laser Induced Fluorescence ◽  
Translational Energy ◽  
Fluorescence Technique ◽  
Ultraviolet Laser ◽  
Reaction Proceeds

Doppler profiles of H and D atoms from the reaction S(1D) with HD and a 1:1 mixture of H2 and D2 have been measured by a laser-induced fluorescence technique with a vacuum ultraviolet laser. An isotopic channel branching ratio of φ (SD + H)/φ (SH + D) is measured to be 0.9 ± 0.1 in the reaction of S(1D) + HD at average collision energy Ecoll = 1.2 kcal/mol. In S(1D) + HD, D2, and H2, the translational energies released are almost the same, 4.6 ± 0.5 kcal/mol for H and D production channels. The measured branching ratio and translational energy release suggest that the reaction proceeds via a long-lived complex formed by insertion.

scholarly journals Accurate Branching Ratio Measurements in 31P(P,g)32S

1975 ◽  
Vol 28 (4) ◽  
pp. 383 ◽  
Author(s):  
SG Boydell ◽  
DG Sargood
Keyword(s):  
Energy Range ◽  
Proton Energy ◽  
Gamma Ray ◽  
Branching Ratio ◽  
Branching Ratios

The reaction 3 1p(p, y)32S has been investigated in the proton energy range 0'4-1'75 MeV. Gamma ray spectra were measured for 2S resonances with Ge(Li) detectors which were carefully calibrated for relative peak efficiencies. Allowance was made for the effect of anisotropies in all the emitted y-rays. The spectra have been analysed to give branching ratios for bound and unbound levels. Comparisons made with previous work reveal some differences.

scholarly journals Accurate Branching Ratio Measurements in 23Na(p, g)24Mg

1975 ◽  
Vol 28 (4) ◽  
pp. 369 ◽  
Author(s):  
SG Boydell ◽  
DG Sargood
Keyword(s):  
Energy Range ◽  
Proton Energy ◽  
Gamma Ray ◽  
Branching Ratio ◽  
Branching Ratios

The reaction 23Na(p, y)24Mg has been investigated in the proton energy range O' 3-1' 75 MeV. Gamma ray spectra were measured for 22 resonances with Ge(Li) detectors which were carefully calibrated for relative peak efficiencies. Allowance was made for the effect of anisotropies in all the emitted y-rays. The speCtra have been analysed to give branching ratios for bound and unbound levels.

scholarly journals Disentangling QCD and new physics in D → πℓ+ℓ−

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Aoife Bharucha ◽  
Diogo Boito ◽  
Cédric Méaux
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
Branching Ratios ◽  
New Physics ◽  
Operator Product ◽  
Beyond The Standard Model ◽  
Spectral Functions ◽  
The Standard Model ◽  
Model Independent ◽  
Weak Annihilation

Abstract In this paper we consider the decay D+ → π+ℓ+ℓ−, addressing in particular the resonance contributions as well as the relatively large contributions from the weak annihilation diagrams. For the weak annihilation diagrams we include known results from QCD factorisation at low q2 and at high q2, adapting the existing calculation for B decays in the Operator Product Expansion. The hadronic resonance contributions are obtained through a dispersion relation, modelling the spectral functions as towers of Regge-like resonances in each channel, as suggested by Shifman, imposing the partonic behaviour in the deep Euclidean. The parameters of the model are extracted using e+e− → (hadrons) and τ → (hadrons) + ντ data as well as the branching ratios for the resonant decays D+ → π+R(R → ℓ+ℓ−), with R = ρ, ω, and ϕ. We perform a thorough error analysis, and present our results for the Standard Model differential branching ratio as a function of q2. Focusing then on the observables FH and AFB, we consider the sensitivity of this channel to effects of physics beyond the Standard Model, both in a model independent way and for the case of leptoquarks.

scholarly journals Time-Resolved Investigation of the Molecular Chemiluminescence SrI(A2∏1/2,3,2,B2∑+→X2∑+) and the Atomic Resonance Fluorescence Sr(53P1→51S0) Following The Pulsed Dye Laser Generation Of Sr(53PJ) in the Presence of CF3I

1995 ◽  
Vol 16 (2) ◽  
pp. 121-138 ◽  
Author(s):  
S. Antrobus ◽  
D. Husain ◽  
Jie Lei ◽  
F. Castaño ◽  
M. N. Sanchez Rayo
Keyword(s):  
Ground State ◽  
Branching Ratio ◽  
Atomic Emission ◽  
Electronic Energy ◽  
Dye Laser ◽  
Pulsed Dye Laser ◽  
Laser Generation ◽  
Buffer Gas ◽  
Resonance Fluorescence ◽  
Time Resolved

A time-resolved investigation is presented of the electronic energy distribution in SrI following the collision of the optically metastable strontium atom, Sr [5s5p(3PJ)], with the molecule CF3I. Sr[5s5p(3PJ)], 1.807 eV above its 5s2(1S0) electronic ground state, was generated by pulsed dye-laser excitation of ground state strontium vapour to the Sr(53P1) state at , λ =689.3 nm {Sr(53P1←51S0)} at elevated temperature (840 K) in the presence of excess helium buffer gas in which rapid Boltzmann equilibration within the 53PJ spin-orbit manifold takes place. Time resolved atomic emission from Sr(53P1→51S0) at the resonance transition and the molecular chemiluminescence from SrI(A2∏1,2,3/2,B2∑+→X2∑+) resulting from reaction of the excited atom with CF3I were recorded and shown to be exponential in character. SrI in the A2∏1/2,3/2 (172.5, 175.4 kJ mol-1) and B2∑+ (177.3 kJ mol-1) states are energetically accessible on collision by direct-I-atomic abstraction between Sr(3P) and CF3I. The first-order decay coefficients for the atomic and molecular emissions are found to be equal under identical conditions and hence SrI(A2∏1/2,3/2, B2∑+) are shown to arise from direct I- atom abstraction reactions. The molecular systems recorded were SrI (A2∏1/2→X2∑+, Δv=0, λ=694 nm), SrI(A2∏3/2→X2∑+, Δv=0, λ=677 nm) and SrI(B2∑+→X2∑+) (Δv=0, λ=674 nm), dominated by the Δv=0 sequences on account of Franck-Condon considerations. The combination of integrated m61ecular and atomic intensity measurements yields estimates of the branching ratios into the specific electronic states, A1/2, A3/2 and B, arising from Sr(53PJ)+CF3I which are found to be as follows: A1/2,1.2 × 10-2; A3/2, 6.7 × 10-3; B, 5.1 × 10-3 yielding ∑SrI(A1/2+A3/2+B)=2.4 × 10-2. As only the X, A and B states SrI are accessible on reaction, assuming that the removal of Sr(53PJ) occurs totally by chemical removal, this yields an upper limit for the branching ratio into the ground state of ca. 98%. The present results are compared with previous time-resolved measurements on excited states of strontium halides that we have reported on various halogenated species resulting from reactions of Sr(53PJ), together with analogous chemiluminescence studies on Sr(3PJ) and Ca(43PJ) from molecular beam measurements.

CONTROLLING ABOVE-THRESHOLD DISSOCIATION BRANCHING RATIOS OF HD+ WITH FEMTOSECOND LASER PULSE TRAIN

2012 ◽  
Vol 11 (04) ◽  
pp. 709-721 ◽  
Author(s):  
QIAN-ZHEN SU ◽  
JIE YU ◽  
KAI-JUN YUAN ◽  
SHU-LIN CONG
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Femtosecond Laser Pulse ◽  
Pulse Train ◽  
Branching Ratio ◽  
Branching Ratios ◽  
Pulse Number ◽  
Molecular Ions ◽  
Quantum Wave ◽  
Energy Dependent

Above-threshold dissociation (ATD) process of the molecular ions HD+ steered by a femtosecond laser pulse train (LPT) is investigated theoretically using the time-dependent quantum wave packet method. Energy-dependent distributions of ATD fragments are analyzed by using an asymptotic-flow expression in the momentum space. It is found that fragment kinetic energy spectra shift to low energy region with increasing pulse number of LPT. The photofragment branching ratio between the 1sσg and 2pσu dissociation channels is sensitive to the pulse number of LPT. The momentum distribution of the ATD fragments is discussed in detail.

scholarly journals Branching Ratio Measurements of the Predissociation of 12C16O by Time-Slice Velocity-Map Ion Imaging in the Energy Region from 106 250 to 107 800 cm–1

2018 ◽  
Vol 122 (41) ◽  
pp. 8136-8142 ◽  
Author(s):  
Xiaoyu Shi ◽  
Hong Gao ◽  
Qing-Zhu Yin ◽  
Yih-Chung Chang ◽  
Roger C. Wiens ◽  
...  
Keyword(s):  
Energy Region ◽  
Branching Ratio ◽  
Time Slice ◽  
Ion Imaging

Cross Sections and Asymmetry Parameters for Formic Acid in the Vacuum-Ultraviolet Energy Range

2020 ◽  
Vol 124 (32) ◽  
pp. 6478-6485
Author(s):  
M. M. Fujimoto ◽  
H. K. Tanaka ◽  
R. R. T. Marinho ◽  
A. Medina ◽  
F. V. Prudente ◽  
...  
Keyword(s):  
Formic Acid ◽  
Energy Range ◽  
Cross Sections ◽  
Vacuum Ultraviolet ◽  
Ultraviolet Energy ◽  
Asymmetry Parameters
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