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Areas of investigation summarized include nitrogen ion-nitrogen molecule collisions; molecular collisions with surfaces; molecular identification from analysis of cracking patterns of selected gases; computer modelling of a quadrupole mass spectrometer; study of space charge in a quadrupole; transmission of the 127 deg cylindrical electrostatic analyzer; and mass spectrometer data deconvolution.
Molecular collisions, formulating description as set of differential equations and developing eigenvectors and eigenvalues of Hermitian matrix associated with coupling
Aerodynamic molecular beam interactions with solid surfaces
The Dynamics of Molecular Collisions Conference focuses on all aspects of molecular collisions--experimental & theoretical studies of elastic, inelastic, & reactive encounters involving atoms, molecules, ions, clusters, & surfaces--as well as half collisions--photodissociation, photo-induced reaction, & photodesorption. The scientific program for the meeting in 2011 included exciting advances in both the core & multidisciplinary forefronts of the study of molecular collision processes. Following the format of the 2009 meeting, we also invited sessions in special topics that involve interfacial dynamics, novel emerging spectroscopies, chemical dynamics in atmospheric, combustion & interstellar environments, as well as a session devoted to theoretical & experimental advances in ultracold molecular samples. Researchers working inside & outside the traditional core topics of the meeting are encouraged to join the conference. We invite contributions of work that seeks understanding of how inter & intra-molecular forces determine the dynamics of the phenomena under study. In addition to invited oral sessions & contributed poster sessions, the scientific program included a formal session consisting of five contributed talks selected from the submitted poster abstracts. The DMC has distinguished itself by having the Herschbach Medal Symposium as part of the meeting format. This tradition of the Herschbach Medal was first started in the 2007 meeting chaired by David Chandler, based on a generous donation of funds & artwork design by Professor Dudley Herschbach himself. There are two such awards made, one for experimental & one for theoretical contributions to the field of Molecular Collision Dynamics, broadly defined. The symposium is always held on the last night of the meeting & has the awardees are asked to deliver an invited lecture on their work. The 2011 Herschbach Medal was dedicated to the contributions of two long standing leaders in Chemical Physics, Professor Yuan T. Lee & Professor George Schatz. Professor Lee’s research has been based on the development & use of advanced chemical kinetics & molecular beams to investigate & manipulate the behavior of fundamental chemical reactions. Lee’s work has been recognized by many awards, including the Nobel Prize for Chemistry in 1986, as well as Sloan Fellow, Dreyfus Scholar, Fellowship in the American Academy of Arts & Sciences, Fellowship in the American Physical Society, Guggenheim Fellow, Member National Academy of Sciences, Member Academia Sinica, E.O. Lawrence Award, Miller Professor, Berkeley, Fairchild Distinguished Scholar, Harrison Howe Award, Peter Debye Award, & the National Medal of Science. Lee also has served as the President of the Academia Sinica in Taiwan (ROC). Professor Schatz’s research group is interested in using theory & computation to describe physical phenomena in a broad range of applications relevant to chemistry, physics, biology & engineering. Among the types of applications that we interested are: optical properties of nanoparticles & nanoparticle assemblies; using theory to model polymer properties; DNA structure, thermodynamics & dynamics; modeling self assembly & nanopatterning; & gas phase reaction dynamics. Among his many awards & distinctions have been appointment as an Alfred P. Sloan Research Fellow, Camille & Henry Dreyfus Teacher-Scholar, the Fresenius Award, Fellow of the American Physical Society, the Max Planck Research Award, Fellowship in the American Association for the Advancement of Science, & election to the International Academy of Quantum Molecular Sciences & the American Academy of Arts & Sciences. Dr Schatz is also lauded for his highly successful work as Editor for the Journal of Physical Chemistry. We requested $10,000 from DOE in support of this meeting. The money was distributed widely among the student & post doctoral fellows & some used to attract the very best scientists in the field. The organizers were committed to encouraging women & minorities as well as encourage the field of Chemical Physics in scientifically developing countries. For example, it has been a tradition of the DMC meeting to offer of order 40 scholarships for students & postdocs to defray registration & travel costs. The benefits of increased graduate student & post doctoral attendance at the meeting cannot be over emphasized. First, these young scientists have the opportunity to present their work by means of the poster session & to a gathering of experts in their field. Secondly the limited size of the meeting allows student & young postdocs to meet & interact directly with experts in their area, to network with their peers at other institutions & become aware of career opportunities. Graduate students & post doctoral fellows are the life blood of our field. Support of their attendance at this & other similar meetings will ensure a continued flow of young talent into many areas of research represented by the DMC meeting & important to DOE.
Adiabatic approximation for nonreactive molecular collisions obtained from variational principle
Subexcitation molecular collisions resonances demonstrated by numerical solution of integral equations for rotational excitation, exhibiting adiabatic approximation limitations
Theory and analysis of relative motion and internal excitation in molecular collisions
The importance of the rigorous treatment of photon angular momentum in molecular-collision processes occurring in the presence of intense radiation is investigated. An alternate approximate treatment, which essentially neglects the angular momentum coupling between the photon and the molecular degrees of freedom by averaging over the angular dependence of the interaction matrix elements, is presented and applied to a model calculation. The degeneracy-averaged results of this calculation compare remarkably well with the results of a rigorous calculation, from which we conclude (with reservation) that the explicit consideration of photoangular momentum coupling in molecular-collision problems is unnecessary.
Funding request for the 26th Dynamics of Molecular Collisions Conference
Distorted wave Magnus /DWM/ approximation for nonreactive molecular collisions, noting applicability in inelastic transition probabilities computation
The 25th The Conference on the Dynamics of Molecular Collisions (DMC) was held from July 12-17, 2015. The Conference provides a unique platform and focal point for the gathering of experimentalists and theoreticians in the field of chemical dynamics. Since its inauguration in 1965, it has played an irreplaceable role in the development of this field and of many distinguished careers. This 25th meeting was highly successful. We held ten oral sessions and four poster sessions. Nobel Laureate Yuan T. Lee presented the keynote lecture. At this meeting, celebrating 50 years of chemical reaction dynamics, one hundred thirty-seven attendees participated, forty-two talks were presented as well as fifty-nine posters.Many attendees remarked that it was the “best meeting of the year.” Results from the meeting and other contributions were collected in a special issue of the Journal of Physical Chemistry A, published December 17, 2015. With this proposal we sought support for students, post-doctoral researchers and junior scientists who needed financial support. The Department of Energy has a large program in gas phase chemistry and many of the speakers and session chairs at the meeting are presently supported by DOE, including Professor Millard Alexander and Carl Lineberger, the recipents of the 2015 Herschbach Prizes that were awarded at the meeting. Funds were used to supplement registration fees for students and post-docs and to cover registration fees for the six selected “hot topic” presentations.
Rotational excitation in diatomic molecular collisions to obtain equations for generalized set of phase shifts
Compound state resonances in molecular collisions, stressing scattering cross sections behavior for deuterium-xenon
Radiative transitions in molecular collision processes taking place in the presence of picosecond pulses are studied within a semiclassical formalism. An expression for adiabatic potential surfaces in the electronic-field representation is obtained, which directly leads to the evaluation of transition probabilities. Calculations with a Landau-Zener-type model indicate that picosecond pulses can be much more effective in inducing transitions than a single long pulse of the same intensity and the same total energy, if the intensity is sufficiently high that the perturbation treatment is not valid.
Nuclear spin effect on expressions for molecular collisions scattering cross sections using diagrammatic techniques
An introductory account of the semiclassical theory of the S-matrix for molecular collision processes is presented, with special emphasis on electronically nonadiabatic transitions. This theory is based on the incorporation of classical mechanics with quantum superposition, and in practice makes use of the analytic continuation of classical mechanics into the complex space of time domain. The relevant concepts of molecular scattering theory and related dynamical models are described and the formalism is developed and illustrated with simple examples - collinear collision of the A+BC type. The theory is then extended to include the effects of laser-induced nonadiabatic transitions. Two bound continuum processes collisional ionization and collision-induced emission also amenable to the same general semiclassical treatment are discussed.
The effect of the laser linewidth on molecular collision processes taking place in a laser field is studied, using an approximation scheme that replaces the actual frequency distribution of the field by a finite number of frequencies and weights. The choice of the frequencies and weights is conveniently accomplished by the method of Gaussian quadrature. Close-coupling calculations are performed on model systems, and the results indicate that the neglect of the laser linewidth may be justified in most collision processes in a laser field.
Collision cross sections direct measurement for determining macroscopic reaction rates in inelastic molecular collision processes in gas dynamics