TY - JOUR

T1 - IR spectroscopic testing of surfaces in water ice and in icy mixtures with prussic acid or ammonia

AU - Rudakova, Aida V.

AU - Sekushin, Vladimir N.

AU - Marinov, Ilya L.

AU - Tsyganenko, Alexey A.

PY - 2009/2/3

Y1 - 2009/2/3

N2 - An experimental technique is developed for spectral studies of ice films deposited at 77 K onto the ZnSe inner windows of a cell, so that the spectra could be registered in the presence of gaseous adsorbate. Pure H20 or D20 ice as well as HCN/D2O and ND3/D 2O mixed icy films with different dopant/water ratios (1:10, 1:5, and 1:1) were investigated. The surface area of ice deposited at 77 K 3/4 O estimated from adsorption measurements was about 160 m2/g. Bands of dangling hydroxyl groups disappear on raising the temperature up to 130-160 K when the changes of bulk absorption provide evidence for a phase transition from amorphous to polycrystalline ice. Surface properties of icy films were characterized by low-temperature adsorption of CO and CHF3. Insertion of small doses of HCN or ammonia does not change the acid/base strength of dangling hydroxyl groups or coordinately unsaturated surface oxygen atoms, but it changes the proportion between the concentrations of these sites as compared with pure water ice. For high dopant concentrations, the dangling hydroxyls were not observed, and the dominant adsorption sites for CO are likely to be the unsaturated oxygen atoms, while serious structural changes occur in the bulk of ices.

AB - An experimental technique is developed for spectral studies of ice films deposited at 77 K onto the ZnSe inner windows of a cell, so that the spectra could be registered in the presence of gaseous adsorbate. Pure H20 or D20 ice as well as HCN/D2O and ND3/D 2O mixed icy films with different dopant/water ratios (1:10, 1:5, and 1:1) were investigated. The surface area of ice deposited at 77 K 3/4 O estimated from adsorption measurements was about 160 m2/g. Bands of dangling hydroxyl groups disappear on raising the temperature up to 130-160 K when the changes of bulk absorption provide evidence for a phase transition from amorphous to polycrystalline ice. Surface properties of icy films were characterized by low-temperature adsorption of CO and CHF3. Insertion of small doses of HCN or ammonia does not change the acid/base strength of dangling hydroxyl groups or coordinately unsaturated surface oxygen atoms, but it changes the proportion between the concentrations of these sites as compared with pure water ice. For high dopant concentrations, the dangling hydroxyls were not observed, and the dominant adsorption sites for CO are likely to be the unsaturated oxygen atoms, while serious structural changes occur in the bulk of ices.

UR - http://www.scopus.com/inward/record.url?scp=61849155219&partnerID=8YFLogxK

U2 - 10.1021/la802792u

DO - 10.1021/la802792u

M3 - Article

AN - SCOPUS:61849155219

VL - 25

SP - 1482

EP - 1487

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 3

ER -