A density functional theory study of the hydrates of NH{sub 3}{center_dot}H{sub 2}SO{sub 4} and its implications for the formation of new atmospheric particles
- Drexel Univ., Philadelphia, PA (United States). Dept. of Chemistry
The interest in tropospheric and stratospheric aerosols has risen in past years. This is primarily due to the fact that aerosols in the troposphere and stratosphere are altering the earth`s climate by scattering radiation directly or indirectly by changing the reflectivity of clouds. They have also been involved in indirectly depleting the Antarctic stratospheric ozone layer by converting relatively inert chlorine species to photochemically reactive species which are well-known ozone-destroying species. Density functional molecular orbital theory was used at the B3LYP/6-311++G(2d,2p)//B3LYP/6-311++G(2d,2p) level of theory to study the hydrates of NH{sub 3}{center_dot}H{sub 2}SO{sub 4}{center_dot}nH{sub 2}O for n = 0--5 and NH{sub 3}{center_dot}(H{sub 2}SO{sub 4}){sub 2}{center_dot}H{sub 2}O. Neutrals of the first four NH{sub 3}{center_dot}H{sub 2}SO{sub 4}{center_dot}nH{sub 2}O clusters (n = 0--4) spontaneously formed and were determined to be hydrogen-bonded molecular complexes of H{sub 2}SO{sub 4}, H{sub 2}O, and NH{sub 3}. Double ions (clusters containing a NH{sub 4}{sup +} cation and a HSO{sub 4}{sup {minus}} anion) spontaneously formed in clusters of NH{sub 3}{center_dot}{approximately}H{sub 2}SO{sub 4}{center_dot}nH{sub 2}O where n = 1--5. The energetics of the hydration and isomerization reactions also were calculated. Double ions are not energetically favorable until NH{sub 3}{center_dot}H{sub 2}SO{sub 4}{center_dot}4H{sub 2}O. The free energy of formation from free NH{sub 3} and H{sub 2}SO{sub 4}{center_dot}nH{sub 2}O had a maximum at n = 3 at room temperature with {Delta}G {approx} {minus}3 kcal/mol. NH{sub 3}{center_dot}(H{sub 2}SO{sub 4}){sub 2}{center_dot}H{sub 2}O was studied to see if NH{sub 3} can initiate new atmospheric particle growth. It has been shown that NH{sub 3} has no role in the initialization of new atmospheric particles.
- OSTI ID:
- 347662
- Journal Information:
- Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Journal Name: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory Journal Issue: 15 Vol. 103; ISSN 1089-5639; ISSN JPCAFH
- Country of Publication:
- United States
- Language:
- English
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