Probing of the hot-band excitations in the photodissociation of OCS at 288 nm by DC slice imaging

2004 ◽  
Vol 82 (6) ◽  
pp. 880-884 ◽  
Author(s):  
Myung Hwa Kim ◽  
Wen Li ◽  
Suk Kyoung Lee ◽  
Arthur G Suits
Keyword(s):  
Cross Section ◽  
Molecular Beam ◽  
Potential Surface ◽  
Imaging Technique ◽  
Branching Ratio ◽  
Translational Energy ◽  
Hot Band ◽  
Anisotropy Parameters ◽  
Slice Imaging ◽  
Central Slice

The photodissociation dynamics of OCS at 288 nm has been investigated using the DC (direct current) slice imaging technique, which is a recently developed high-resolution "slicing" approach that directly measures the central slice of the photofragment distribution in imaging experiments. By analyzing a DC sliced image of S(1D2) photofragments we observe dissociation originating from OCS molecules excited up to v2 = 4 in the molecular beam. The measured translational energy distribution was used to determine the branching ratio for the contribution from each initial bending state (0 v2 0) of OCS and relative photodissociation cross section ratios compared to v2 = 1. Large negative anisotropy parameters determined as a function of the S(1D2) fragment recoil speed indicate that the photodissociation of OCS at 288 nm occurs exclusively from the 11A′′(1Σ–) bending excited potential surface that can be accessed through a perpendicular transition.Key words: DC slicing imaging, OCS, photodissociation, hot-band excitation.

Near-Surface Aggregation of Sn In Heavily Sn-Doped GaAs Films Grown By Molecular Beam Epitaxy

1985 ◽  
Vol 43 ◽  
pp. 368-369
Author(s):  
S. H. Chen
Keyword(s):  
Molecular Beam Epitaxy ◽  
Cross Section ◽  
Electron Spectroscopy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Secondary Ion Mass Spectrometry ◽  
Specimen Preparation ◽  
Near Surface ◽  
Gaas Films ◽  
Secondary Ion

Sn has been used extensively as an n-type dopant in GaAs grown by molecular-beam epitaxy (MBE). The surface accumulation of Sn during the growth of Sn-doped GaAs has been observed by several investigators. It is still not clear whether the accumulation of Sn is a kinetically hindered process, as proposed first by Wood and Joyce, or surface segregation due to thermodynamic factors. The proposed donor-incorporation mechanisms were based on experimental results from such techniques as secondary ion mass spectrometry, Auger electron spectroscopy, and C-V measurements. In the present study, electron microscopy was used in combination with cross-section specimen preparation. The information on the morphology and microstructure of the surface accumulation can be obtained in a fine scale and may confirm several suggestions from indirect experimental evidence in the previous studies.

Crossed-beam studies of radical reaction dynamics:

1994 ◽  
Vol 72 (3) ◽  
pp. 660-672 ◽  
Author(s):  
R. Glen Macdonald ◽  
Kopin Liu Argonne ◽  
David M. Sonnenfroh ◽  
Di-Jia Liu
Keyword(s):  
Cross Sections ◽  
Molecular Beam ◽  
Radical Reaction ◽  
Reaction Cross ◽  
Translational Energy ◽  
Vibronic State ◽  
State Distribution ◽  
Title Reaction ◽  
Vibrational Ground State ◽  
Reaction Cross Sections

The title reaction has been studied in a crossed molecular beam apparatus. Both the product state distributions and the translational energy dependence of the reaction cross sections were measured under single collision conditions. Excellent agreement was found over a wide temperature range (26–3800 K) between rate constants deduced from the translational excitation function and recent thermal kinetic data. The rotational state distribution was found to be very cold compared to the reaction exothermicity, and could be described by a Boltzmann temperature of 110 K for all K-doublet levels. The vibronic state distribution was also found to be cold, with 70% of the products formed in the vibrational ground state. By comparing the molecular beam results for vibronic state distributions with those obtained from recent bulb experiments, it was conjectured that there appears to be a strong correlation between rotation in the reactants and bending excitation in the products.

scholarly journals Cross Section Prediction for Inclusive Production of Z Boson in pp Collisions at s=14 TeV: A Study of Systematic Uncertainty due to Scale Dependence

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Hasan Ogul ◽  
Kamuran Dilsiz
Keyword(s):  
Cross Section ◽  
Production Cross Section ◽  
Z Boson ◽  
Production Cross ◽  
Branching Ratio ◽  
Leading Order ◽  
Proton Proton ◽  
Proton Collisions ◽  
Central Values ◽  
Proton Proton Collisions

Prediction of Z→l+l- production cross section (where l±=e±,μ±) in proton-proton collisions at s=14 TeV is estimated up to next-to-next-to-leading order (NNLO) in perturbative QCD including next-to-leading order (NLO) electroweak (EW) corrections. The total inclusive Z boson production cross section times leptonic branching ratio, within the invariant mass window 66<mll<116 GeV, is predicted using NNLO HERAPDF2.0 at NNLO QCD and NLO EW as σZTot=2111.69-26.92+26.31 (PDF) ±11 (αs) ±17 (scale) -30.98+57.41 (parameterization and model). Theoretical prediction of the fiducial cross section is further computed with the latest modern PDF models (CT14, MMHT2014, NNPDF3.0, HERAPDF2.0, and ABM12) at NNLO for QCD and NLO for EW. The central values of the predictions are based on DYNNLO 1.5 program and the uncertainties are extracted using FEWZ 3.1 program. In addition, the cross section is also calculated as functions of μR and μF scales. The choice of μR and μF for scale variation uncertainty is further discussed in detail.

ELECTROWEAK MEASUREMENTS FROM RUN II AT THE TEVATRON

2004 ◽  
Vol 19 (06) ◽  
pp. 794-807
Author(s):  
T. R. WYATT
Keyword(s):  
Cross Section ◽  
Branching Ratio ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Total Decay Width ◽  
Decay Modes ◽  
Leptonic Decays ◽  
Vector Bosons ◽  
First Time ◽  
Intermediate Vector

The CDF and DØ detectors were fully commissioned for physics running in Run II at the Tevatron [Formula: see text] collider in early 2002. Since then both experiments have collected data samples corresponding to an integrated luminosity of around ∫L=200 pb -1 at a [Formula: see text] centre-of-mass energy of [Formula: see text]. Datasets corresponding ∫L=120 pb-1 have been analyzed for physics so far. Recent electroweak measurements from Run II are reviewed. Cross section times branching ratio measurements (σ· Br ) are presented for the intermediate vector bosons (IVB's) in their leptonic decay modes: W→ℓν and Z→ℓ+ℓ-. For the first time, a combination of the σ· Br results from the CDF and DØ experiments is made; this includes using a consistent choice of the total inelastic [Formula: see text] cross section for the luminosity determinations of the two experiments. Quantities derived from these σ· Br values are also updated. These include: R ℓ the ratio of the σ· Br values for W and Z; Br (W→ℓν), the leptonic branching ratio of the W; and Γw, the total decay width of the W. Other measurements using events containing W and Z leptonic decays are presented, including studies that probe the QCD phenomenology of W/Z production and searches for events containing two intermediate vector bosons.

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