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68 results on '"Hunton, D. E."'

53. Gas Phase Interactions in the Shuttle Environment

Author

AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, Hunton,D E, Calo,J M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, Hunton,D E, and Calo,J M

Abstract

A quadrupole mass spectrometer was flown on STS-4. A retarding potential grid located in the ion source distinguished between high and low energy ionic and neutral species in the Shuttle environment. The bulk of the neutral water molecules entering the mass spectrometer appear to be thermal. In contrast, a considerable fraction of water ions, which are formed from charged transfer reactions with ambient 0+, have energies greater than thermal. The high energy species are attributed to nonreactive collisions between the thermal water ions and the high energy incoming flux of ambient neutrals. The energy distributions of the ions are affected more by these interactions because of their greater collision cross sections., Proceedings of the AIAA Shuttle Environment and Operations II Conference Held on 13-15 Nov 85 at Houston, TX., paper no. AIAA-85-6055-CP.

Published
1985

54. Unimolecular Decay of Metastable CO3(-)

Author

PENNSYLVANIA STATE UNIV UNIVERSITY PARK DAVEY LAB, Hunton,D. E., Albertoni,C. R., Mark,T. D., Castleman,A. W. , Jr, PENNSYLVANIA STATE UNIV UNIVERSITY PARK DAVEY LAB, Hunton,D. E., Albertoni,C. R., Mark,T. D., and Castleman,A. W. , Jr

Published
1984

55. Studies of the Laser Photodissociation of CO3(-) and CO3(-) -Water Complexes

Author

PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF CHEMISTRY, Castleman,A. W. , Jr., Hunton,D. E., Lindeman,T. G., Lindsay,D. N., PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF CHEMISTRY, Castleman,A. W. , Jr., Hunton,D. E., Lindeman,T. G., and Lindsay,D. N.

Abstract

Sponsored in part by Grant NSF-ATM79-13801.

Published
1983

57. Photodissociation of CO3(-). Evidence for a Long-Lived Excited State

Author

PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF CHEMISTRY, Hunton,D. E., Hofmann,M., Lindeman,T. G., Castleman,A. W. , Jr, PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF CHEMISTRY, Hunton,D. E., Hofmann,M., Lindeman,T. G., and Castleman,A. W. , Jr

Published
1983

67. In situ HNO3to NOyinstrument comparison during SOLVE

Author

Ballenthin, J. O., Thorn, W. F., Miller, T. M., Viggiano, A. A., Hunton, D. E., Koike, M., Kondo, Y., Takegawa, N., Irie, H., and Ikeda, H.

Abstract

Measurements of HNO3mixing ratios from the chemical ionization mass spectrometer have been critically compared with simultaneous measurements of total gas phase NOyfrom the NO chemiluminescence detector aboard the NASA DC‐8 aircraft during the SAGE 3 Ozone Loss and Validation Experiment (SOLVE). The data were obtained in the arctic upper troposphere and lower stratosphere in the winter of 1999–2000. A brief comparison to the NOyinstrument aboard the NASA ER‐2 is also presented. The time responses, detection limits, relative precision, and stability of relative calibrations for the instruments were in excellent agreement throughout the mission. However, the average slope of the HNO3to NOycorrelation was 1.13 ± 0.03 overall and 1.06 ± 0.03 in stratospheric air, indicating that the two measurements had a systematic calibration offset. Possible sources for the offset error are presented, and methods to reduce the calibration error in future flights are suggested.

Published
2003
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68. Particle Formation by Ion Nucleation in the UpperTroposphere and Lower Stratosphere.

Author

Lee, S.-H., Reeves, J. M., Wilson, J. C., Hunton, D. E., Viggiano, A. A., Miller, T. M., Ballenthin, J. O., and Lait, L R.

Subjects
*TROPOSPHERE, *STRATOSPHERE, *NUCLEATION, *THERMODYNAMICS
Abstract

Unexpectedly high concentrations of ultrafine particles were observed over a wide range of latitudes in the upper troposphere and lower stratosphere. Particle number concentrations and size distributions simulated by a numerical model of ion-induced nucleation, constrained by measured thermodynamic data and observed atmospheric key species, were consistent with the observations. These findings indicate that, at typical upper troposphere and lower stratosphere conditions, particles are formed by this nucleation process and grow to measurable sizes with sufficient sun exposure and low preexisting aerosol surface area. Ion-induced nucleation is thus a globally important source of aerosol particles, potentially affecting cloud formation and radiative transfer. [ABSTRACT FROM AUTHOR]

Published
2003
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