2026-09-21T12:55:31Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/72742 2023-07-11 col_2142_5131 col_2142_8888 com_2142_5130 com_2142_8887 com_2142_234

Eden, James G. Eden, James G. Carney, Paul S. Cunningham, Brian T. Gruebele, Martin McCall, Benjamin J. Houlahan, Thomas 2015-01-21T19:47:36Z 2015-01-21T19:47:36Z 2014-12 2015-01-21 2014-12 We report on the development of a new laboratory tool which is suitable both for generating and quickly cooling short-lived molecules, and also for studying the kinetics and dynamics that take place at the rotational level during the expansion process. By integrating a microplasma device with a supersonic nozzle, temperatures as low as 50 K were achieved for molecules having lifetimes shorter than 40 ns and excitation (internal) energies ≳ 11 eV. Additionally, final temperatures ranging from 90 K to 900 K for a set of nested electronic states were observed in the He2 excimer, and a highly non-equilibrium rotational distribution was recorded for the lowest of these nested states. This rotational distribution was analyzed with a kinetic mode and shown to be due primarily to collisional excitation transfer and rotational relaxation. Since collisions are the means by which the supersonic expansion process cools atoms/molecules, this result perhaps demonstrates a fundamental restriction on which molecular states can and cannot be effectively cooled in a supersonic expansion. The rate constant for rotational relaxation within the He2(d3Σu+) state was determined to be (9.4 ± 0.1) × 10-13 cm3s-1, while the rate constant for collisional excitation transfer between rotational levels of the He2(e3Πg) and He2(d3Σu+) states was found to scale as (9.8 ± 5.9 × 10-14 cm3s-1)exp(-(6.4 × 10-3)/ ΔE*B). Item withdrawn by Laura Spradlin (lspradl2@illinois.edu) on 2014-08-07T21:52:47Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Houlahan_Thomas.pdf: 14547007 bytes, checksum: 8703d2837c86e52f240847d778dbca60 (MD5) Made available in DSpace on 2015-01-21T19:47:36Z (GMT). No. of bitstreams: 1 Thomas_Houlahan.pdf: 14547007 bytes, checksum: 8703d2837c86e52f240847d778dbca60 (MD5) http://hdl.handle.net/2142/72742 en Copyright 2014 Thomas J. Houlahan, Jr. supersonic cooling plasma jet short-lived molecular states Pulsed plasma microjets: a new tool for the investigation of plasma kinetics and molecular spectroscopy text Electrical & Computer Eng 1933 Electrical & Computer Engr 1200 University of Illinois at Urbana-Champaign Dissertation Ph.D. PHD:Electr & Computer Eng-UIUC 10KS1200PHD