Bulletin of the American Physical Society
42nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 56, Number 5
Monday–Friday, June 13–17, 2011; Atlanta, Georgia
Session N1: AMO Science for Laboratory and Astrophysical Environments |
Hide Abstracts |
Chair: Arati Dasgupta, Naval Research Laboratory Room: A601 |
Thursday, June 16, 2011 10:30AM - 11:00AM |
N1.00001: Cooling and Infrared Emission due to Molecular Collisional Excitation in Astrophysical Environments Invited Speaker: Non-thermal popluations of molecules in a variety of astronomical environments, including photodissociation regions, X-ray dominated regions, and protoplanetary disks, are controlled by collisional excitation and quenching of their rovibrational levels. The important colliders are the dominant neutral species: H, He, and H$_2$. Resulting emission lines are primary cooling transitions and can be observed by current and upcoming IR/submillimeter observatories including Spitzer, Herschel, SOFIA, and ALMA. Modeling these environments, however, requires large-scale computation of collisional excitation processes. The status, needs, and astrophysical applications for important molecular targets will be reviewed including H$_2$, HD, CO, H$_2$O, and NH$_3$. [Preview Abstract] |
Thursday, June 16, 2011 11:00AM - 11:30AM |
N1.00002: Charge-Exchange Experiments with Highly Charged Ions and Their Relevance to Astrophysics Invited Speaker: The wide range of highly-charged ions (HCIs) and charge states produced in the electron cyclotron resonance ion source allows one to study fundamental atomic-physics processes both for their intrinsic value, and for their importance to understanding astrophysical phenomena. These phenomena include ionization fractions of solar/stellar plasmas; charge exchange with comets, circumstellar clouds, and planetary {\&} satellite exospheres. Presented will be recent experimental and theoretical results for absolute single and multiple charge-exchange cross sections for HCI-neutral collisions, together with spectra of X-ray emissions following the charge-exchange collision. In collaboration with Stojan Madzunkov, John MacAskill, Ara Chutjian, Jet Propulsion Lab. [Preview Abstract] |
Thursday, June 16, 2011 11:30AM - 12:00PM |
N1.00003: Laboratory Astrophysics for Current and Future X-ray Satellites Invited Speaker: Although the analysis of even CCD-resolution X-ray spectra benefits from good-quality atomic data, the high-resolution X-ray data available from existing X-ray satellites have shown the absolute need for atomic data of all stripes: wavelengths, absorption cross sections, and collisional and radiative rates. This process will continue with upcoming telescopes such as Astro-H and IXO. I will describe the successes of both theoretical calculations and laboratory measurements as well as the many remaining needs and the science that hinges upon them. These include, amongst other issues, accurate wavelength measurements in the soft X-ray band, calibrated line ratios of selected strong lines, and high-resolution absorption cross sections for common atoms. I will also discuss the release of v2.0 of the AtomDB, a unified collection of atomic data suitable for analysis of astrophysical X-ray spectra. [Preview Abstract] |
Thursday, June 16, 2011 12:00PM - 12:30PM |
N1.00004: Probing Long-Range Configurations of Molecular Hydrogen Invited Speaker: Very long-range molecular configurations are of interest in a variety of contexts, for example, in the astro-chemistry of cold molecular clouds and in planetary atmospheres, including our own. Such states can be more than 10 times the size of the ground state and often possess energies above multiple ionization potentials and dissociation limits resulting in diverse and complex decay dynamics. Many of these configurations possess a double-well character arising from the interaction of molecular Rydberg states, repulsive doubly-excited states, and ionic states. The ion pair in hydrogen, an unusual molecular configuration consisting of one proton shrouded in a cloud of two electrons separated very far from the other proton, is notoriously difficult to create and study. We report results from on our investigation of such states using resonantly enhanced multi-photon ionization via the E,F v = 6, J = 0, 1, and 2 states to probe the H(n=1) + H(n=3) dissociation threshold energy region. Both molecular and atomic ion production were detected as a function of wavelength by using a time-of-flight mass spectrometer. Below threshold a series of highly excited vibrational levels of several long range states are observed. Above threshold broad resonances are observed with energies that agree well with the predictions of a mass-scaled Rydberg formula for bound states of the H+ H- ion pair. Measured linewidths, quantum defects, and rotational dependences are reported for ion pair principal quantum numbers in the range of n = 130 to 206. Our new results can be compared to recent experimental work using a different excitation scheme, which was the first spectroscopic observation of heavy Rydberg states in hydrogen [1], and new ab initio theoretical work [2]. \\[4pt] [1] M. O. Vieitez, T. I. Ivanov, E. Reinhold, C. A. de Lange, and W. Ubachs, J. Phys. Chem. A 113 13237 (2009).\\[0pt] [2] A. Kirrander, J. Chem. Phys. 133, 121103 (2010). [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700