scholarly journals Accessing the molecular frame through strong-field alignment of distributions of gas phase molecules

2018 ◽  
Vol 376 (2115) ◽  
pp. 20170158 ◽  
Author(s):  
Katharine L. Reid
Keyword(s):  
Gas Phase ◽  
Strong Field ◽  
Laboratory Frame ◽  
Theoretical Chemistry ◽  
Single Parameter ◽  
Gaussian Form ◽  
Gas Phase Molecules ◽  
Photoelectron Angular Distribution ◽  
Complete Set ◽  
Molecular Frame

A rationale for creating highly aligned distributions of molecules is that it enables vector properties referenced to molecule-fixed axes (the molecular frame ) to be determined. In the present work, the degree of alignment that is necessary for this to be achieved in practice is explored. Alignment is commonly parametrized in experiments by a single parameter, , which is insufficient to enable predictive calculations to be performed. Here, it is shown that, if the full distribution of molecular axes takes a Gaussian form, this single parameter can be used to determine the complete set of alignment moments needed to characterize the distribution. In order to demonstrate the degree of alignment that is required to approach the molecular frame, the alignment moments corresponding to a few chosen values of are used to project a model molecular frame photoelectron angular distribution into the laboratory frame. These calculations show that needs to approach 0.9 in order to avoid significant blurring to be caused by averaging. This article is part of the theme issue ‘Modern theoretical chemistry’.

Imaging of strong field dissociative single and double ionization channels of N2O

2017 ◽  
Vol 31 (29) ◽  
pp. 1750215 ◽  
Author(s):  
Feras Afaneh ◽  
Horst Schmidt-Böcking
Keyword(s):  
Angular Distribution ◽  
Laser Pulse ◽  
Momentum Distribution ◽  
Strong Field ◽  
Double Ionization ◽  
Photoelectron Angular Distribution ◽  
Ionization Processes ◽  
Elliptically Polarized ◽  
Molecular Frame ◽  
Ionization Rates

In this paper, we study single and double ionizations of N2O in a short elliptically polarized 800 nm laser pulse using the COLTRIMS technique. The molecular-frame photoelectron angular distribution and the ion sum-momentum distribution of single and double ionizations of N2O molecules are reported for the single ionization dissociative channel NO[Formula: see text] + N and the double ionization dissociative channel NO[Formula: see text] + N[Formula: see text]. The ionizations of multiple orbitals for the two studied dissociative channels were identified via studying the orientation dependent ionization rates for their KERs. The results show that the shape of the ionizing orbitals governs the single and double ionization processes of N2O.

scholarly journals X-ray diffractive imaging of controlled gas-phase molecules: Toward imaging of dynamics in the molecular frame

2020 ◽  
Vol 152 (8) ◽  
pp. 084307 ◽  
Author(s):  
Thomas Kierspel ◽  
Andrew Morgan ◽  
Joss Wiese ◽  
Terry Mullins ◽  
Andy Aquila ◽  
...  
Keyword(s):  
Gas Phase ◽  
Diffractive Imaging ◽  
X Ray ◽  
Gas Phase Molecules ◽  
Molecular Frame

scholarly journals Rapid compressions in a captive bubble apparatus are isothermal

2003 ◽  
Vol 95 (5) ◽  
pp. 1896-1900
Author(s):  
Wenfei Yan ◽  
Stephen B. Hall
Keyword(s):  
Hydrostatic Pressure ◽  
Gas Phase ◽  
Pulmonary Surfactant ◽  
First Order ◽  
First Order Kinetics ◽  
Gas Phase Molecules ◽  
Actual Change ◽  
Phase Temperature ◽  
Two Phases ◽  
Interfacial Films

Captive bubbles are commonly used to determine how interfacial films of pulmonary surfactant respond to changes in surface area, achieved by varying hydrostatic pressure. Although assumed to be isothermal, the gas phase temperature (Tg) would increase by >100°C during compression from 1 to 3 atm if the process were adiabatic. To determine the actual change in temperature, we monitored pressure (P) and volume (V) during compressions lasting <1 s for bubbles with and without interfacial films and used P · V to evaluate Tg. P · V fell during and after the rapid compressions, consistent with reductions in n, the moles of gas phase molecules, because of increasing solubility in the subphase at higher P. As expected for a process with first-order kinetics, during 1 h after the rapid compression P · V decreased along a simple exponential curve. The temporal variation of n moles of gas was determined from P · V >10 min after the compression when the two phases should be isothermal. Back extrapolation of n then allowed calculation of Tg from P · V immediately after the compression. Our results indicate that for bubbles with or without interfacial films compressed to >3 atm within 1 s, the change in Tg is <2°C.

Computational UV Spectra for Amorphous Solids of Small Molecules

2021 ◽  
Author(s):  
Austin Michael Wallace ◽  
Ryan C. Fortenberry
Keyword(s):  
Carbon Dioxide ◽  
Interstellar Medium ◽  
Small Molecules ◽  
Gas Phase ◽  
Amorphous Solids ◽  
Uv Spectra ◽  
Ammonia Water ◽  
Gas Phase Molecules ◽  
High Level

Ices in the interstellar medium largely exist as amorphous solids composed of small molecules including ammonia, water, and carbon dioxide. Describing gas-phase molecules can be readily accomplished with current high-level...

scholarly journals Strongly aligned gas-phase molecules at free-electron lasers

2015 ◽  
Vol 48 (20) ◽  
pp. 204002 ◽  
Author(s):  
Thomas Kierspel ◽  
Joss Wiese ◽  
Terry Mullins ◽  
Joseph Robinson ◽  
Andy Aquila ◽  
...  
Keyword(s):  
Gas Phase ◽  
Free Electron ◽  
Free Electron Lasers ◽  
Gas Phase Molecules

scholarly journals Evolutionary Models of Interstellar Chemistry

1992 ◽  
Vol 150 ◽  
pp. 205-210
Author(s):  
Sheo S. Prasad
Keyword(s):  
Gas Phase ◽  
Chemical Processes ◽  
Evolutionary Models ◽  
Evolutionary Perspective ◽  
Interstellar Chemistry ◽  
Interstellar Clouds ◽  
Dynamical Equilibrium ◽  
Chemical Models ◽  
Gas Phase Molecules ◽  
Fixed Condition

Evolutionary chemical models are ultimately unavoidable for a full understanding of interstellar clouds. They include not only the chemical processes but also the dynamical processes by which the modeled object came to be the way it is. From an evolutionary perspective, dark cores may be ephemeral objects and dynamical equilibrium an exception rather than norm. Evolutionary models have numerous advantages over “classical” fixed condition equilibrium models. They have the potential to provide more elegant explanations for the observed inter-cloud and intra-cloud chemical differences. The problem of the depletion of gas phase molecules by condensation onto the grain may also be less serious in evolutionary models. Hence, these models should be actively developed.

scholarly journals Chemical Models of Collapsing Envelopes

2000 ◽  
Vol 197 ◽  
pp. 51-60
Author(s):  
Edwin A. Bergin
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Chemical Evolution ◽  
Molecular Ions ◽  
Polar Molecules ◽  
Mass Star ◽  
Chemical Models ◽  
Gas Phase Molecules ◽  
Low Mass

We discuss recent models of chemical evolution in the developing and collapsing protostellar envelopes associated with low-mass star formation. In particular, the effects of depletion of gas-phase molecules onto grain surfaces is considered. We show that during the middle to late evolutionary stages, prior to the formation of a protostar, various species selectively deplete from the gas phase. The principal pattern of selective depletions is the depletion of sulfur-bearing molecules relative to nitrogen-bearing species: NH3 and N2H+. This pattern is shown to be insensitive to the details of the dynamics and marginally sensitive to whether the grain mantle is dominated by polar or non-polar molecules. Based on these results we suggest that molecular ions are good tracers of collapsing envelopes. The effects of coupling chemistry and dynamics on the resulting physical evolution are also examined. Particular attention is paid to comparisons between models and observations.

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