Issue 10 Volume 41 May 16, 2003

20030034684 Air Force Research Lab., Edwards AFB, CA, USA
Observation of the Cyclic Water Hexamer in Solid Parahydrogen
Fajardo, Mario E.; Tam, Simon; Jul 2001; 6 pp.; In English
Contract(s)/Grant(s): Proj-2303
Report No.(s): AD-A410499; AFRL-PR-ED-TP-2001-167; No Copyright; Avail: CASI; A02, Hardcopy
We present infrared (IR) absorption spectra of cryogenic parahydrogen solids doped with small water clusters. We observe
a sequence of peaks shifted to the red by approx. 15/cm from the absorptions of cyclic water clusters in liquid helium droplets
K. Nauta and R.E. Miller Science 287 293(2000); this sequence includes the peak due to the cyclic isomer of the water
hexamer: cyc-(H2O)6. We believe this is only the second spectroscopic observation of isolated cyc-(H2O)6, and the first report
of the IR spectrum of the isolated cluster in the solid phase.
DTIC
Infrared Absorption; Infrared Spectra; Para Hydrogen; Solid Cryogens; Water; Cyclic Compounds
20030034685 Air Force Research Lab., Edwards AFB, CA, USA
Single and Double Infrared Transitions in Rapid Vapor Deposited Parahydrogen Solids: Application to Sample
Thickness Determination and Quantitative Infrared Absorption Spectroscopy
Tam, Simon; Fajardo, Mario E.; Apr 2001; 43 pp.; In English
Contract(s)/Grant(s): Proj-2303
Report No.(s): AD-A410500; AFRL-PR-ED-TP-2001-074; No Copyright; Avail: CASI; A03, Hardcopy
We present a convenient method for determining the thickness of a cryogenic parahydrogen (pH2) solid from its infrared
(IR) absorption spectrum. Millimeters-thick pH2 solids of exceptional optical clarity can be produced by the rapid vapor
deposition method. Doping of these pH2 solids is readily accomplished by co-deposition of the desired impurities, making
them excellent hosts for high- resolution matrix isolation spectroscopy. The intensities of the IR ‘double’ transitions
Q1(0)+S0(0) and S1(0)+S0(0) of the pH2 host are insensitive to the matrix microstructure and to the presence of dopants, so
these absorptions are especially well suited for thickness determinations. We calibrate the integrated absorption intensities of
these two bands against the sample thicknesses determined from transmission interference fringes appearing in the same
experimental spectra; we report: aQ1(0)+S0(0) = 4.84(+ or -0.l3)xl0(exp -14) cu cm/s, and aS1(0)+S0(0) = 0.35(+ or
-0.02)xl0(exp -14) cu cm/s (95\% confidence). We also discuss several other advantages of rapid vapor deposited pH2 solids
as hosts for quantitative IR absorption spectroscopy of dopant species.
DTIC
Para Hydrogen; Spectroscopy; Vapor Deposition; Additives; Infrared Spectra; Rocket Propellants
20030034710 Oak Ridge National Lab., TN, Lockheed Martin Energy Research, Corp., Oak Ridge, TN
Very Appoximate Theory for Gas Transport in a Polymer Foam
Kirkpatrick, J. R.; Dec. 1999; 36 pp.; In English
Report No.(s): DE2002-750985; No Copyright; Avail: Department of Energy Information Bridge
The author is involved with a project that requires calculation of the flow of gas through thin sheets of a flexible polymer
foam. Essentially, the foam is a collection of interconnected spherical holes in the polymer matrix. When the material is made,
its porosity is in the range of 60 - 70\%. Initially, the sheets are roughly a millimeter thick. In the application, the sheets are
compressed between solid surfaces so that their thickness is reduced to approximately 50 - 75\% of the original (thereby
reducing the porosity to as low as 20\%). The project requires calculating gas transport in the longitudinal direction (in other
words, parallel to the thin section of the sheets and perpendicular to the direction of compression). The transport calculations
must be done in three different flow regimes. First, with gas pressures high enough so that the gas in the pores is in the
continuum regime and thus the transport is governed by the usual equations for flow of a compressible gas in a porous
medium. Second, with gas pressures low enough so that the flow is in the free molecular region. In the third regime, the foam
is filled with a carrier gas (with pressure high enough to be in continuum) and the flow of interest is that of a small amount
of an additional gas. In this third regime, the driving force is diffusion of the trace gas in the carrier.
NTIS
Gas Transport; Foams
20030034711 Air Force Research Lab., Edwards AFB, CA, USA
New Materials Design
Boatz, Jerry; May 2002; 37 pp.; In English
Contract(s)/Grant(s): Proj-2303
Report No.(s): AD-A410667; AFRL-PR-ED-VG-2002-118; No Copyright; Avail: CASI; A03, Hardcopy
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