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Anicich, V. G.

Publications and source records attributed to Anicich, V. G..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

An index of the literature for bimolecular gas phase cation-molecule reaction kinetics

This is an index to the literature for gas phase bimolecular positive ionmolecule reactions. Over 2300 references are cited. Reaction rate coefficients and product distributions of the reactions are abstracted out of the original citations where available. This index is intended to cover the literature from 1936 to 2003. This is a continuation of several surveys: the original (Huntress Astrophys. J. Suppl. Ser., 33, 495 (1977)), an expansion (Anicich and Huntress, Astrophys. J. Suppl. Ser. 62, 553 (1986)), a supplement (Anicich, Astrophys. J. Suppl. Ser. 84, 215 (1993)), and an evaluation (Anicich, V. G. J. Phys. Chem. Ref. Data 22,1469 (1993b). The Table of reactions is listed by reactant ion.

reaction kinetics↗
NASA NTRS1996

(abstract) Ion-Molecule Reactions at Your Finger Tips

A standalone search engine is described along with a database of ion-molecule kinetics. The engine is available for either Macintosh or IBM/PC computers. The engine will search a supplied database of ion-molecule kinetics data for two body reactions and positive ions. The database includes data found in various publications and reference works written by the author. Currently that database has over 10 600 reaction entries and uses over 1 000 referenced citations. Searches of the database can be by either reactants or products and either ions or neutrals. Narrowing searches can be made on up to three specifications. Reports of the searches are either viewed on the screen or printed. The reports also include the short list of references cited.

ion-molecule reactions search engine database ion-↗
NASA NTRS1996

Reactions of CH3(+) with C2N2, CH2CHCN, and HC3N: A Low-Pressure/High-Pressure Study

The association of CH3(+) with the three molecules C2N2, CH2CHCN, and HCCCN has been examined using ion cyclotron resonance (ICR) and selected ion flow tube (SIFT) techniques at room temperature. In each reaction, the mean lifetime of the complex (CH3 x N-=C-R(+))(sup *) formed in the association has a major influence on the outcome of the reaction and the product channels that are observed using ICR and SIFT. Termolecular rate coefficients are reported for the association of CH3(+) + C2N2 for the bath gases M = He, Ar, N2, and C2N2. k(sub 3) = 8.2 x 10(exp-24) cm(sup 6)/s (M = C2N2). In each system the association product channel occurs in competition with exothermic bimolecular channels. The complex lifetimes in all three systems are in the range 30-70 microsec. Very rapid ion-molecule association reactions have been observed in several systems of hydrocarbons and nitriles, and the implications for Titan ion chemistry are discussed briefly.

McEwan, M. J.↗
NASA NTRS1996

Ion-Molecule Chemistry in Titan's Ionosphere

We present a summary of the information available from laboratory studies of ion-molecule reactions that is relevant to the chemistry occuring in Titan's ionopshere. Reaction information from the literature has been collated and we have measured many new reations, including some ion-atom reactions.

planetary atmospheres Titan ion molecule ionospher↗
NASA NTRS1995

Deuterium Exchange in the Systems of H2O+/H2O and H3O+/H2O

Using tandem mass spectrometry various water ion interactions were observed. These reactions consisted of a series of charge transfer, proton transfer, and isotopic exchange steps. The experimental data sets consist of variations of ion abundances over a neutral pressure range. An expected sequence of isotopic exchange reactions is given along with differential equation solutions & reaction rate data.

Spectroscopy Deuterium Proton Ion Atmospheric Scie↗
NASA NTRS1994

(abstract) Distribution of Unimolecular Lifetimes in Ion-Molecule Association Reactions

The distribution of unimolecular lifetimes of ion-molecule complexes formed in association reactions has been measured by ion cyclotron double-resonance. The mean unimolecular lifetimes of (H(sub 2)C(sub 6)N(sub 2)(sup +))(sup *) and (CH(sub 3)CN.CH(sub 3)(sup +))(sup *) were determined to be 180 (micro)s and 140 (micro)s respectively. A theoretical examination of the distribution of lifetimes of (CH(sub 3)CN.CH(sub 3)(sup +))(sup *) was conducted using a RRKM model. The RRKM distribution, when modified by experimental constraints, was found to be a good approximation of the experimentally determined lifetime distribution. The lifetimes for unimolecular dissociation and radiative relaxation, and the absolute efficiency of collisional relaxation are also reported.

unimolecular lifetimes ion-molecule complexes RRKM↗
NASA NTRS1994

H2O-Rich Interstellar Grain Mantles: An Equilibrium Picture

Experiments simulating the codeposition of molecular hydrogen and water ice on interstellar grains demonstrate that amorphous water ice at 12 K can incorporate a substantial amount of H2, up to a molar ratio of H2/H2O=0.53.

molecular hydrogen↗
NASA NTRS1993

A survey of bimolecular ion-molecule reactions for use in modeling the chemistry of planetary atmospheres, cometary comae, and interstellar clouds - 1993 supplement

This is a supplement to a previous paper (Anicich & Huntress 1986). It is a survey of bimolecular positive ion-molecule reactions with potential importance to the chemistry of planetary atmospheres, cometary comae, and interstellar clouds. This supplement covers the literature from 1986 through 1991, with some additional citations missed in the original survey. Over 200 new citations are included. A table of reactions is listed by reactant ion, and cross-references are provided for both ionic and neutral reactants and also for both ionic and neutral products.

Anicich, V. G.↗
NASA NTRS1993

Statistical modeling of capture, association, and exit-channel dynamics in the CH3(+)/CH3CN system

The ion-molecule CH3(+) + CH3CN reaction is presently modeled by means of a master equation treatment incorporating weak collisions. The parameter required for the Rice-Ramsberger-Kassel-Markus (RRKM) treatment is derived from an ab initio investigation of the energy surface in question, and a means of including the capture rate coefficients in the RRKM approach is developed in which only the hindered dipole rotation is coupled in the reaction coordinate at large separations. Unimolecular rate coefficients for the (CH3CNCH3+)-activated complex are calculated for all product channels in the 300-600 K temperature range.

Smith, S. C.↗
NASA NTRS1992

Formaldehyde reactions in dark clouds

The low-pressure reactions of formaldehyde (H2CO) with D(+), D2(+), D3(+), and He(+) are studied by the ion-cyclotron resonance technique. These reactions are potential loss processes for formaldehyde in cores of dark interstellar clouds. The deuterated reactants represent direct analogs for protons. Rate coefficients and branching ratios of product channels have been measured. Charge transfer is observed to be the dominant reaction of H2CO with D(+), D2(+), and He(+) ions. Only the D3(+) reaction exhibits a proton-transfer channel. All reactions proceed at rate coefficients near the collision limit. Proton-deuteron exchange reactions are found to be inefficient processes in the formaldehyde system.

Sen, A. D.↗
NASA NTRS1992

Dielectric constant of liquid alkanes and hydrocarbon mixtures

The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.

NASA Program Exobiology↗
NASA NTRS1992

Sulfur and nitrogen reactions for cometary comae ion chemistry

The low pressure reactions of sulfur dioxide, carbon disulfide, and hydrazine with H2O+ and H3O+ were studied by the ion cyclotron resonance technique. These reactions are potentially important for sulphur chemistry in cometary comae. Rate coefficients and branching ratios of product channels are presented.

NASA Center JPL↗
NASA NTRS1991

Quantification of UV stimulated ice chemistry: CO and CO2

Recent laboratory experiments are presented that show that during photolysis of the pure ices there is evidence of the interconversion of CO to CO2 and CO2 to CO using Lyman alpha (1216A) radiation. In addition, there is a substantial amount of another substance being produced. This substance is evident by its infrared absorption peak at 2235 cm(-1). It is believed that this new peak is due to carbon suboxide, C3O2. CO and CO2 have already been detected in comets, and C3O2 has been suggested as a cometary from radiation of CO. Comparisons are made between our results at 1215A and proton radiation experiments and radiation at other wavelengths. The suggestion is that the processing of ices is energy dependent, i.e., dependent on the type of radiation. Several difficult problems have to be solved before these radiation conversions can be quantified. The steps that we are taking to quantify the kinetics are discussed.

Anicich, V. G.↗
NASA NTRS1986

A survey of bimolecular ion-molecule reactions for use in modeling the chemistry of planetary atmospheres, cometary comae, and interstellar clouds

All bimolecular positive ion-molecule reactions reported from 1965 to 1985 for temperatures below 1000 K are included in the present survey of those ion-molecule reactions pertinent to the chemistries of planetary atmospheres, cometary comae, and interstellar clouds. This survey is intended as an update of the first, by Huntress (1977). The tabular presentation is organized according to reactant ion, with cross-references for both the ionic and the neutral reactants as well as the ionic and neutral products.

Anicich, V. G.↗
NASA NTRS1986

Chemistry of chlorine in dense interstellar clouds

Laboratory experiments and theoretical modeling show that the chemistry of chlorine is fairly simple in dense interstellar clouds, with Cl and HCl as the only species whose fractional abundances are significant. The estimated fraction of gas-phase chlorine present as HCl lies between 25-65 percent, in good agreement with the recent observations of the ground state HCl transition by Blake, Keene, and Philips (1985). These results, combined with the observational limits on HCl, indicate that chlorine is not severely depleted in dense interstellar clouds.

Blake, G. A.↗
NASA NTRS1986

Ion-molecule reactions of hydrocarbon ions in C2H2 and HCN

Rate coefficients and product distributions have been determined for reaction of the ions C(x)H(y)+ (x ranging from 1 to 4, and y ranging from 0 to 4) with C2H2 and HCN. The measurements were obtained using the ion cyclotron resonance technique at 298 K. In several reactions an association product was observed at pressures as low as 0.000001 torr, and in these cases stabilization of the intermediate was assumed to be by photon emission. Most of the reaction studied yield ions having a larger carbon skeleton than the reactant ion. These reactions provide routes for building large organic and organonitrogen molecules in combustion zones of unsaturated hydrocarbon flames and in astrochemical environments.

Anicich, V. G.↗
NASA NTRS1984

The chemistry of phosphorus in dense interstellar clouds

Laboratory experiments show that the ion-molecule chemistry of phosphorus is significantly different from that of nitrogen in dense interstellar clouds. The PH3 molecule is not readily formed by gas-phase, ion-molecule reactions in these regions. Laboratory results used in a simple kinetic model indicate that the most abundant molecule containing phosphorus in dense clouds is PO.

Thorne, L. R.↗