HDO Diffusion Kinetics in Pure and Acid-Dosed Single-Crystal Ice Multilayers

Livingston, Frank E.; George, Steven M.

doi:10.4028/www.scientific.net/ddf.160-161.25

Cited by 8 publications

(37 citation statements)

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“…The solid line through the data points for methanol, acetic acid, formic acid, and HCl hydrate diffusion represents a diffusion activation barrier of E d ) 16.8 ( 1.5 kcal/mol and a diffusion preexponential of D o ) 1.7 × 10 9(0.4 cm 2 /s. Figure 8 shows that the diffusion kinetics for these molecules are very similar to the diffusion kinetics for HDO diffusion in pure ice [10][11][12] and HCl-dosed ice. 11 A vacancy-mediated mechanism has been proposed earlier for H 2 O diffusion in ice at T < 223 K. 53,54 Based on the similar kinetics for H 2 O diffusion and the diffusion of HCl hydrates, a vacancy-mediated mechanism was also proposed for HCl hydrate diffusion.…”

Section: A Bulk Diffusion Mechanism In Icementioning

confidence: 63%

“…Figure 8 shows that the diffusion kinetics for these molecules are very similar to the diffusion kinetics for HDO diffusion in pure ice [10][11][12] and HCl-dosed ice. 11 A vacancy-mediated mechanism has been proposed earlier for H 2 O diffusion in ice at T < 223 K. 53,54 Based on the similar kinetics for H 2 O diffusion and the diffusion of HCl hydrates, a vacancy-mediated mechanism was also proposed for HCl hydrate diffusion. 16 The results for methanol provided by this study, together with additional results for formic and acetic acid from other investigations, 34 add considerably to the preponderance of results displaying the same diffusion kinetics.…”

Section: A Bulk Diffusion Mechanism In Icementioning

confidence: 63%

“…More recent LRD studies have explored the diffusion of weak organic acids, such as formic acid (HCOOH) and acetic acid (CH 3 COOH), in ice. 34 A comparison of the Arrhenius results for the diffusion of these species, together with the previous LITD results for H 2 O isotope diffusion in ice, [10][11][12]15 is shown in Figure 8. The diffusion coefficients and diffusion kinetic parameters measured using LRD depth profiling are summarized in Table 1.…”

Section: Resultsmentioning

confidence: 95%

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General Trends for Bulk Diffusion in Ice and Surface Diffusion on Ice

2002

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Experimental measurements of bulk diffusion in ice and surface diffusion on ice were performed using laser resonant desorption (LRD) techniques. Bulk diffusion in ice was examined using ice sandwich structures and continuous source experiments together with LRD depth-profiling analysis. Surface diffusion was monitored using prepare-refill-probe LRD experiments. New experimental results were obtained for the bulk diffusion of NH 3 and CH 3 OH. These species probably exist as hydrates in the ice. The LRD measurements for CH 3 OH hydrate diffusion, combined with previous results, provide evidence for a vacancy-mediated diffusion mechanism. The diffusion rates for NH 3 hydrates are much larger than diffusion rates for H 2 O self-diffusion in ice and are attributed to the disruption of the ice lattice. LRD prepare-refill-probe experiments revealed that surface diffusion was not measurable for almost all of the species examined on ice. Only butane displayed a measurable surface mobility that was attributed to its unique size and chemical nature. These new measurements of bulk diffusion in ice and surface diffusion on ice should be useful in developing our understanding of kinetic processes in and on ice that are relevant to heterogeneous atmospheric chemistry and ice core analysis.

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Section: A Bulk Diffusion Mechanism In Icementioning

confidence: 63%

Section: A Bulk Diffusion Mechanism In Icementioning

confidence: 63%

Section: Resultsmentioning

confidence: 95%

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General Trends for Bulk Diffusion in Ice and Surface Diffusion on Ice

2002

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“…The DCl LITD signals do not display a linear loss versus time. The absolute initial desorption rate of ∼6.0 × 10 -3 BL/s for DCl is less than the absolute desorption rate of ∼0.03 BL/s for D 2 O at 155.0 K. Similar to DNO 3 , the nonlinear loss of DCl is assigned to the concurrent DCl isothermal desorption and DCl diffusion into the underlying ice multilayer. ,,,, …”

Section: Resultsmentioning

confidence: 89%

“…In contrast, the DNO 3 LITD signals do not display a linear loss versus time. The absolute initial DNO 3 desorption rate of ∼0.01 BL/s is less than the absolute D 2 O desorption rate of ∼0.02 BL/s at 160.0 K. The nonlinear desorption behavior for DNO 3 is attributed to the competition between DNO 3 isothermal desorption and DNO 3 diffusion into the underlying ice film. ,,,, …”

Section: Resultsmentioning

confidence: 89%

Effect of HNO₃ and HCl on D₂O Desorption Kinetics from Crystalline D₂O Ice

Livingston

George

1998

J. Phys. Chem. A

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The presence of trace species may perturb H2O desorption kinetics from ice surfaces and alter the stability of atmospheric ice particles. To investigate the effects of atmospheric species on H2O desorption kinetics from crystalline ice, the D2O desorption kinetics from pure and HNO3- and HCl-dosed crystalline D2O ice multilayers on Ru(001) were investigated using isothermal laser-induced thermal desorption (LITD) measurements. The D2O desorption kinetics were studied for D2O ice film thicknesses of 25−200 BL (90−730 Å) and initial acid coverages of 0.5−3.0 BL for HNO3 and 0.3−5.0 BL for HCl. Arrhenius analysis of the D2O desorption rates from pure D2O crystalline ice at T = 150−171 K yielded a desorption activation energy of E d = 13.7 ± 0.5 kcal/mol and a zero-order desorption preexponential of νo = (3.3 ± 0.7) × 1032 molecules/(cm2 s). The absolute D2O desorption rates were ∼3−5 times smaller for D2O ice films exposed to HNO3. The D2O desorption kinetics from HNO3-dosed ice were E d = 11.3 ± 0.4 kcal/mol and νo = (5.0 ± 0.9) × 1028 molecules/(cm2 s). In contrast, the absolute D2O desorption rates were ∼2 times larger for D2O ice films exposed to HCl. The D2O desorption kinetics from HCl-dosed ice were E d = 14.2 ± 0.6 kcal/mol and νo = (3.7 ± 0.8) × 1033 molecules/(cm2 s). The changes in the D2O isothermal desorption kinetics were independent of DNO3 and DCl coverages. The adsorbate-induced perturbations are believed to be associated with the formation of stable hydrate cages and reduced D2O mobility in HNO3-dosed ice and the creation of defects and enhanced D2O mobility in HCl-dosed ice. The effects of HNO3 and HCl on the D2O desorption kinetics indicate that the growth, stability, and lifetimes of atmospheric ice particles should be altered by the presence of adsorbates on the ice surface.

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