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Using the molecular dynamics method, the joint absorption of oxygen and nitrate ions by water clusters is studied in terms of the polarizable model of flexible molecules. Significant fluctuations are observed in the number of hydrogen bonds in the clusters during the addition of NO3− ions to water-oxygen aggregates. Dielectric permittivity noticeably changes upon the addition of O2 molecules to water clusters and nitrate ions to oxygen-containing water clusters. After the absorption of oxygen molecules and nitrate ions, water clusters markedly lose the ability to IR absorption. The Raman spectrum of a medium formed from disperse aqueous system, oxygen, and nitrate ions displays a greater number of bands than the spectrum of a system of pure water clusters.

Interactions of (Br−)i(H2O)50−i clusters (0 ≤ i ≤ 6) with molecular oxygen is studied by the molecular dynamics method using flexible molecule model. Values of real and imaginary parts of permittivity decrease in the 0 ≤ ω ≤ 3500 cm−1 frequency range with increasing number of bromine ions in a cluster. The ability of cluster to absorb IR radiation decreases, whereas the reflectance and Raman light scattering remains nearly unchanged. An increase in the content of Br− ions in the cluster lowers the power of emitted IR radiation and decreases the amount of active electrons participating in the interaction with IR radiation. However, when the concentration of Brions becomes substantially higher (at i = 5 and 6), the values of emitted power and the number of active electrons are restored to the values that are typical for water cluster in the absence of Br− ions. At i ≥ 3, repelling Br− ions acquire kinetic energy, which is sufficient to remove molecular oxygen from the system.

Interactions of (SiO2)50 clusters with 10, 20, 30, or 40 water molecules are studied by molecular dynamics method. Flat SiO2 nanoparticle covered with a water layer is formed after the inclusion of water molecules into the cluster. As a rule, the integral intensity of IR and Raman spectra lowers after the absorption of H2O molecules by the cluster. The power of IR radiation emitted by the cluster increases nonmonotonically with the addition of water molecules to the cluster. The absorption of water molecules by the cluster leads to a significant increase in the absorption coefficient and only a slight increase in the refractive index. The number of electrons participating in the interaction with electromagnetic radiation increases with the addition of water molecules to the cluster.

however, only two of them, nitrogen(II) oxide and nitrogen(IV) oxide, are stable under ordinary conditions and actively participate in the natural and industrial nitro� gen cycles. Nitrogen oxides ( ) are of great impor� tance for many atmospheric reactions. radical is the most reactive of them; it is formed in the dark and is regulated by the chemical reactions occurring in the night atmosphere. When interacting with water, nitro� gen oxides form nitric acid ( ), which is not only the main component of acid rain, but also governs the main process of removing nitrogen oxides from atmo� sphere. Nitric acid plays the key role in the chemistry of polar stratosphere. It is involved in the formation of ozone holes. Nitrogen oxides directly participate in the formation and decomposition of the tropospheric ozone. Under the action of sunlight, nitrogen dioxide is transformed into monoxide NO, which, in turn, forms by interacting with oxygen. Ozone and peroxide radicals are also involved in this cycle. The physical properties of nitrous oxide ( ), which is one of the most prevailing greenhouse gases, has been studied in greatest detail. The dielectric properties and IR spectra of water clusters interacting with nitrous oxide molecules ( ) were investigated in [1, 2]. The uptake of nitrogen monoxide (NO) mol� ecules by water clusters and their structure and stabil� ity were considered in [3], while the absorption, reflection, and emission spectra were studied in [4, 5]. 2 NO ,NO, 23 NO , 2 NO , 25 NO

The interactions of a 6O2 + (H2O)50 system with two, four, or six Cl− ions are studied by the molecular dynamics method. The integral intensity of IR and Raman spectra decreases with an increase in the number of Cl− ions surrounding the system. The values of real and imaginary parts of dielectric permittivity increase with the rise in the frequency reaching maxima in the 850 ≤ ω ≤ 950 cm−1. As a result of interactions between ions and the formed (O2)6 (H2O)50 cluster, the pattern of the reflection spectrum of IR radiation becomes smoother. The interaction between 6O2 + (H2O)50 system and Cl− ions leads to the substantial increase in the power of emitted radiation. With time, Cl− ions gradually leave the interaction zone with the system. Maximum residence time of the last ion near the system boundary does not exceed 3 ps. Cl− ions located closer to O2 molecules do not penetrate into the depth of an (O2)6 (H2O)50 cluster.

IR absorption, reflection, and emission spectra of aqueous disperse systems that absorbed molecules of nitric oxide are calculated. In order to reveal the effect of the absorption of NO molecules on the dielectric prop- erties of water clusters with different sizes, clusters are divided into two groups. The first group consists of clusters containing two to ten water molecules, while the second group contains from 11 to 20 H 2 O molecules. Six systems of clusters are studied, e.g., (H 2 O) n , and (NO) 2 (H 2 O) n with 2 ≤ n ≤ 10 and 11 ≤ n ≤ 20 ranges. An increase in the cluster size in each group leads to the amplification of absorption, reflection, and the power of emission of IR radi- ation. The doubling of the NO concentration in the disperse system results in weak changes in the absorption of IR radiation, reduces the reflection and decreases the number of electrons participating in the interaction with external IR radiation, as well as significantly lowers the power of thermal radiation emitted by the system.

Absorption and reflection IR spectra of aqueous disperse systems that absorbed carbon oxide molecules are calculated. Systems of small and large clusters containing 2 ≤ n ≤ 10 and 11 ≤ n ≤ 20 water molecules, respectively, are studied. Each cluster can absorb one or two carbon oxide molecules. Both real and imaginary parts of dielectric permittivity of disperse systems depend on the number of adsorbed CO molecules to a greater extent than that of water molecules in clusters. The integral intensity of the absorption of IR radiation by cluster systems increases after the absorption of carbon oxide molecules by clusters. However, the ability to absorb and reflect IR radiation decreases with an increase in the concentration of absorbed CO molecules. Upon the growth of heteroclusters due to addition of water molecules, integral intensity of the absorption of thermal radiation can be enhanced or damped. In general, the clusterization and capture of CO molecules by clusters result in an anti-greenhouse effect.

Absorption of ethane molecules by water clusters containing 10–20 molecules is studied by the molecular dynamics method. The (H2O)n (I), C2H6(H2O)n (II), and (C2H6)2(H2O)n (III) cluster systems are composed on the basis of specific statistical weights. Spectral characteristics of system and single clusters are determined in the frequency range of 0 ≤ ω ≤ 1000 cm−1. In this frequency range, both real and imaginary parts of dielectric permittivity decrease monotonically after the absorption of C2H6 molecules by an aqueous ultradispersed system. Integral coefficient of IR absorption increases, while average (over frequency) reflection coefficient decreases after the absorption of ethane molecules. The intensity of IR scattering by the systems of clusters containing C2H6 molecules lowers. Maximal values of radiation power for water clusters with various sizes are balanced with the capture of ethane molecules by the clusters, whereas oscillations in the size dependence of the density of electrons that are active with respect to IR radiation decrease.

The structure of water clusters that have absorbed ethane molecules is studied by the molecular dynamics method. Structural analysis is performed by the construction of Voronoi polyheda for oxygen atoms and hybrid polyheda whose centers coincide with the centers of oxygen atoms and the faces are formed according to the positions of hydrogen atoms. The (H2O)20 cluster can retain no more than four ethane molecules remaining at the same time stable. When a water cluster adds more than four ethane molecules, the volumes of Voronoi polyheda acquire values close to the volume per molecule in the bulk liquid water. As the number of ethane molecules in a water cluster increases, the number of hydrogen atoms adjacent to oxygen, as well as the average number of units in cyclic formations composed of hydrogen atoms, also increases. In this case, the number of H-O-H angles formed by the nearest geometric neighbors close to 89° becomes dominant. The coefficient of nonsphericity reflecting the local arrangement of hydrogen atoms around the oxygen atoms decreases as the C2H6 molecules are added to water cluster and approaches to the value of this coefficient for the rhombic dodecahedron in the case of adsorption of six ethane molecules.

Autocorrelation functions of the total dipole moment of clusters composed of H2O and N2O molecules are calculated in terms of the molecular dynamics method. The IR absorption and reflection spectra of systems composed of (H2O)i, N2O(H2O)i, and (N2O)2(H2O)i clusters (2 ≤ i ≤ 20) are obtained on the basis of these functions. Frequency-dependent dielectric permittivity of clusters increases after the absorption of N2O molecules. The absorption coefficient of cluster systems with trapped N2O molecules increases at low frequencies and decays at frequencies ω > 500 cm−1. The inclusion of N2O molecules increases also reflection coefficient R and changes the pattern of R(ω) spectra. The absorption of IR radiation increases with the number of H2O molecules in clusters. Dielectric losses also increase with an increase in i number upon the absorption of N2O molecules. The number of electrons interacting with an incident electromagnetic wave increases upon the capture of N2O molecules.

The (CO2)i(H2O)10 clusters with the kinetic energy corresponding to a temperature of 233 K is simulated by the molecular dynamics method. The stability of these clusters with respect to thermal, mechanical, and dielectric perturbations, as well as to the absorption of CO2 molecules, is studied. It is shown that the cluster composed of 10 water molecules remains thermodynamically stable if it captures one or two CO2 molecules. Clusters are absolutely unstable when 3 ≤ i ≤ 9. A metastable state of clusters is achieved at i > 9.

Autocorrelation functions of translational and angular velocities of H 2 O and CO 2 molecules in (CO 2 ) i (H 2 O) 10 clusters that are generated by the molecular dynamics method, as well as their frequency spectra, are calculated. Self-diffusion coefficients of molecules in clusters are determined. The IR spectra thus obtained and frequency-dependent dielectric permittivity of the clusters indicate the enhancement of absorption of Earth' thermal radiation by these aggregates with an increase in the number of CO 2 molecules in the aggregates. Dielectric losses also increase with the i number.

The simulation of the absorption of CO2 molecules by the (H2O)10 cluster is performed by the molecular dynamics method using the modified TIP4P model of water. The detailed structure of (CO2)i(H2O)10 clusters (0≤i≤11) is analyzed by the statistic geometry method based on the construction of the Voronoi polyhedra. The obtained distributions of the geometric elements of polyhedra indicate the significant changes in the structure of a cluster after the absorption of one CO2 molecule. Only polyhedra characterizing the structure of unstable water clusters that absorbed six or seven CO2 molecules demonstrate a nonsphericity close to the ideal tetrahedron. Linear CO2 molecule tends to be oriented in a cluster so that the average angle formed by this molecule and permanent dipole moments of water molecules would be equal to about 30°.