Theoretical understanding of adlayer structure,thermal stability and electronic property of graphene molecules

The geometry of hexafluorotribenzo[a,g,m]coronene with n-carbon alkyl chains [FTBC-Cn (n = 4, 6, 8, 12)] and their supramolecule self-assembly on a highly oriented pyrolytic graphite (HOPG) surface has been optimized by molecular dynamics simulations using COMPASS force field at 0 K, 298 K, 333 K and 353 K. Electronic properties and intermolecular interactions in graphene supramolecule assembly have been studied by the first principle methods based on the density functional theory (DFT). It is indicated that the thermal stability and electronic properties of graphene molecules can be tunable by attaching alkyl chains to a triangular graphene sheet, and changing the length of the alkyl chain, and self-assembling on a certain substrate. The main results are as follows. The geometry and energy gap of the FTBC-Cn single molecule and their supramolecule self-assembly on HOPG are both stable with the changes of the temperature from 0 K to 353 K and the number of carbon atoms on the alkyl chain. The simulation results of geometry, energy gap as well as STM images of graphene supramolecule assembly are in good agreement with the corresponding experimental results in room temperature. Furthermore, the electronic properties of graphene supramolecule assembly at the temperatures of 0 K, 333 K and 353 K are also predicted. When a triangular graphene molecule attached with six alkyl chains, the energy gaps are increased and stabilized at the temperature from 0 K to 353 K. After FTBC-Cn molecule self-assembly on a HOPG substrate, the energy gap is reduced but still stable.     

First-principles study of small palladium clusters on NiAl(1 1 0) alloy surface

Theoretical calculations focused on the geometry, stability, electronic and magnetic properties of small palladium clusters Pd_n (n=1–5) adsorbed on the NiAl(1 1 0) alloy surface were carried out within the framework of density functional theory (DFT). In agreement with the experimental observations, both Ni-bridge and Al-bridge sites are preferential for the adsorption of single palladium atom, with an adsorption energy difference of 0.04 eV. Among the possible structures considered for Pd_n (n=1–5) clusters adsorbed on NiAl(1 1 0) surface, Pd atoms tend to form one-dimensional (1D) chain structure at low coverage (from Pd₁ to Pd₃) and two-dimensional (2D) structures are more stable than three-dimensional (3D) structures for Pd₄ and Pd₅. Furthermore, metal-substrate bonding prevails over metal–metal bonding for Pd cluster adsorbed on NiAl(1 1 0) surface. The density of states for Pd atoms of Pd/NiAl(1 1 0) system are strongly affected by their chemical environment. The magnetic feature emerged upon the adsorption of Pd clusters on NiAl(1 1 0) surface was due to the charge transfer between Pd atoms and the substrate. These findings may shade light on the understanding of the growth of Pd metal clusters on alloy surface and the construction of nanoscale devices.     

Morphology of Cn thin films (50 ⩽ n < 60) on graphite: Inference of energy dissipation during hyperthermal deposition

Low energy cluster beam deposition, LECBD, under UHV conditions has been used to generate thin films comprising monodispersed non-IPR fullerenes, C_n, 50 ? n < 60, on pyrolithic graphite surfaces (HOPG). The morphology of the resulting C_n deposits has subsequently been studied by ex situ atomic force microscopy. Deposition experiments were carried out under nominally normal incidence and at hyperthermal incident kinetic energies, E₀, varied between 1 and 40 eV. Surface temperatures during deposition, T_s, were varied from 300 K to the desorption onset of ～700 K. Initial sticking of C_n cages is governed by the lateral density of step edges, which act as pinning and nucleation centres for migrating cages. Consequently in the early deposition stages, the surface exhibits large areas of empty terraces, while the step edges themselves are well-decorated. The terraces in turn become decorated by dendritic C_n islands in later deposition stages. Both, the mean size of these 2D islands and the mean distance between nearest islands, δ, scale with the size of the terraces. When increasing the primary kinetic energy, the fractal-like islands become smaller and less dendritic in shape. The mean initial sticking coefficient decays exponentially with increasing E₀. The island topography has also been found to depend sensitively on the deposition temperature. Instead of the dendritic/fractal islands generated at room temperature, densely packed islands terminated by smooth rims are observed upon deposition at elevated temperatures. We rationalize our findings in terms of a three step deposition process involving: (i) conversion of perpendicular E₀ into hyperthermal surface parallel gliding/sliding motion, (ii) friction–dissipation of this surface-parallel kinetic energy within an (unexpectedly large) mean free path Λ followed by (iii) thermal diffusion. Λ, is observed to scale with E₀ and T_s.     

Ultrasonic and DFT study of intermolecular association through hydrogen bonding in aqueous solutions of d(−)-arabinose

The experimental measurements of density, viscosity and ultrasonic velocity of aqueous d-arabinose solutions were carried out as functions of concentration (0.1 ≤ m [mol kg^? 1] ≤ 1.0) and temperature (303.15 ≤ T [K] ≤ 323.15). The isentropic compressibility (β_s), acoustic impedance (Z), hydration number (H_n), intermolecular free length (L_f), classical sound absorption (α/f²)_class and shear relaxation time (τ) were calculated by using the measured data. These parameters have been interpreted in terms of solute–solvent interactions. The quantum chemical calculations were performed to study the hydrogen bonding in interacting complex formed between α-D-arabinopyranose in ¹C₄ conformation and water molecules. Computations have been done by using Density Functional Theory (DFT) method at B3LYP/6-31+g(d) level of theory to study the equilibrium structure of α-d-arabinose, α-D-arabinopyranose–water interacting complex and vibrational frequencies. The solution phase study was carried out using Onsager's reaction field model in water solvent. The computed and scaled vibrational frequencies are in good agreement with the main features of the experimental spectrum when seven water molecules are considered explicitly with α-D-arabinopyranose in ¹C₄ conformation. The interaction energy (E_total), hydrogen bond lengths and dipole moment (μ_m) of the interacting complex are also presented and discussed with in the light of solute–solvent interactions.     

Room-temperature chemisorption of chloroethylenes on Si(1 1 1)7 × 7: formation of surface vinyl,vinylidene and their chlorinated derivatives

Chemisorption of a family of six chloroethylenes (C₂H₃Cl, 1,1-C₂H₂Cl₂, cis-1,2-C₂H₂Cl₂, trans-1,2-C₂H₂Cl₂, C₂HCl₃, and C₂Cl₄) on Si(1 1 1)7 × 7 at room temperature (RT) has been investigated by vibrational electron energy loss spectroscopy (EELS). The characteristic vibrational EELS features have been used to identify the prominent surface species upon RT adsorption. Like ethylene, C₂H₃Cl has been found to predominantly adsorb in a di-σ bonding geometry to the Si surface, while 1,1-C₂H₂Cl₂, cis- and trans-1,2-C₂H₂Cl₂, C₂HCl₃ and, to a lesser extent, C₂Cl₄ appear to undergo dechlorination upon adsorption to form chlorinated vinyl adspecies involving single-σ bonding structures. Evidence of vinylidene (>CCH₂) has been obtained for the first time on a semiconductor surface for the adsorption of 1,1-C₂H₂Cl₂. The present work illustrates that the molecular structure and the Cl content of chloroethylenes play a crucial role in controlling not only the adsorption geometry but also the extent of dechlorination and the resulting adspecies upon RT adsorption on Si(1 1 1).     

Self-induced polarization rotation of laser beam in fullerene (C70) solutions

Nonlinear self-rotation of elliptically polarized laser pulses (λ = 532 nm, τ_FWHM ~ 12 ns) in toluene, benzene and binary mixture (toluene + ethanol) solutions of fullerene C₇₀ has been investigated experimentally. Absolute values and signs of the nonlinear refractive indices (n₂) and nonlinear optical susceptibilities χ⁽³⁾(ω, ? ω, ω) of C₇₀ solutions in toluene and benzene at different values of polarization ellipse (θ = 0.2 ÷ 0.8) have been determined. High-resolution transmission electron microscope studies of C₇₀ solutions showed that in toluene + ethanol mixtures ball-shaped C₇₀ clusters are formed with particle sizes in the range ~ 100 ÷ 500 nm. It has been demonstrated, that the clusters sizes depend on the C₇₀ concentration and volume fraction of ethanol in toluene. Correlation between the processes of C₇₀ clusters formation in solutions and the values of polarization self-rotation angle of transmitted laser beam has been demonstrated. Physical mechanisms of laser induced optical activity in fullerene solutions have been discussed.     

Anomalous scaling behaviour of cobalt cluster size distributions on graphite,epitaxial graphene and carbon-rich (6√3 × 6√3)R30°

The influence of the underlying interface on adsorption of cobalt (Co) is investigated by comparing the nucleation and growth of Co at room temperature on three carbon (C) surfaces, i.e. highly oriented pyrolytic graphite (HOPG), epitaxial graphene/SiC(0001) (hereafter abbreviated as EG) and precursor of EG i.e. C-rich (6√3 × 6√3)R30°/SiC(0001) (hereafter abbreviated as 6√3). On all three surfaces, Co adopts Volmer–Weber growth mode via formation of three-dimensional dome-shaped nanoclusters. Co clusters formed on 6√3 surface are smaller but denser than Co/HOPG or Co/EG. Scaling analysis reveals a critical nucleus size, i* = 1 (atom) and the smallest stable cluster (i* + 1) would be a dimer. Co/HOPG and Co/EG have the same order of magnitude for their cluster densities and sizes. Scaling analyses however show that the i* for Co/EG (i* = 3) is larger than Co/HOPG (i* = 0) and in this respect the smallest stable cluster would be tetramer and monomer respectively. This difference is attributed to the influence of an interface situated between graphene and SiC bulk. It appears that EG is more inert than HOPG towards the adsorption of Co and may act as a better substrate to host Co clusters.     

Formation of binary clusters by molecular ion irradiation

In the present study, we have observed silicon–carbon cluster ions (Si_nC_m⁺) emitted from a Si(1 0 0) surface under irradiation of reactive molecular ions, such as C₆F₅⁺, at 4 keV, 1 μA/cm². The cluster Si_n up to n=8 and “binary” cluster Si_nC up to n=6 are clearly detected for the C₆F₅⁺ irradiation. Stoichiometric clusters (Si_nC_m n=m) except SiC⁺ and other binary clusters which contain more than two carbon atoms (m≥2) were scarcely observed. The observed clusters show a yield alternation between odd and even n. The intensities of Si₄, Si₆ and Si₅C clusters are relatively higher than those of the neighboring clusters. In the case of Si₅C, it is considered that doped carbon atom acts as silicon atom. These results imply that the recombination through the nascent cluster emission and subsequent decomposition takes place during the cluster formation.     

Photoelectron spectroscopy study of irradiation damage and metal–sulfur bonds of thiol on silver and copper surfaces

Self-assembled 1-dodecanethiol monolayers (SAMs) on silver and copper surfaces have been characterized with X-ray photoelectron spectroscopy (XPS) using both the synchrotron radiation and conventional Mg Kα excitation. Irradiation-induced changes in thiolate SAMs on Cu and Ag were observed. The identification of the sulfur species has been done. Results obtained confirm earlier studies of n-alkanethiols on silver. On copper (C₁₂S/Cu), the observed S 2p spectrum is quite broad but the use of different excitation energies enabled us to identify four sulfur species on the surface. A S 2p_3/2 component of copper thiolate is observed at 162.6 eV. Three more doublets (161.9 eV, 163.2 eV and 163.8 eV) have been observed to develop during irradiation and they are assigned to chemisorbed sulfur on copper, to different dialkylsulfides and to sulfur–sulfur bonding.     

Facile Preparation and characterization of zinc phosphate with self-assembled flower-like micro-nanostructures

The three-dimensional flower-like zinc phosphate [Zn₃(PO₄)₂·4H₂O] micro-nanostructures was synthesized by a microwave-assisted sonochemical method in the absence of template under ambient conditions. The effects of reaction temperature of water bath and reactant concentrations on the particle size and morphology of flower-like zinc phosphate were studied. The scanning electron microscopy, transmission electron microscopy, X-ray diffraction and infrared spectroscopy were used to characterize the samples. The results showed that the three-dimensional flower-like zinc phosphate is composed of self-assembled two-dimensional nanosheets. The average thickness of two-dimensional nanosheet was 35–40 nm, and 5–12 layers of nanosheets formed a layered flower with an average thickness of 220–540 nm. The reaction temperatures of water bath and reactant concentrations are the key factors to synthesize perfect three-dimensional flower-like zinc phosphate. The self-assembly is main growth mechanism to form the flower-like zinc phosphate.     

Self-assembled antidots in La2/3Sr1/3MnO3 thin films

In this work, we report on the controlled fabrication of a self-assembled network of antidots in highly epitaxial La_2/3Sr_1/3MnO₃ thin films grown on top of SrTiO₃ (1 0 0) oriented substrates. To promote self-assembly process, it is fundamental to select a unique surface atomic termination of the STO substrates and the appropriate growth conditions. The evolution of the structural and magnetic properties as a function of deposition parameters is analyzed to clarify the growth mechanism leading to the formation of this self-assembled network of antidots. This morphology is of high interest envisaging a new route for the design and fabrication of oxide-based magnetoelectronic devices.     

Mixed self-assembled monolayers of Co-porphyrin and n-alkane phosphonates on gold

The present work focuses on the surface immobilization by self-assembly of pure and mixed Co-porphyrin (Co-Porph-PO₃H₂) and n-alkane phosphonic acids (n-C_nH_2n + 1PO₃H₂; n = 4, 5 and 10) from n-butanol solutions on gold substrates. The stability, amount, and packing of the phosphonic molecules attached to the Au (111) surface were investigated by electrochemical reductive desorption studies, and monolayers' thickness was estimated by ellipsometry. The morphological changes induced by the adsorption of n-decane phosphonic acid on gold were analysed by scanning tunnelling microscopy. The redox behavior of Co-Porph-PO₃H₂ SAMs was assessed in organic medium and compared that of Co-Porph-CO₂CH₃ precursor in solution, confirming the self-assembly of the metalloporphyrin molecules. With the purpose of reducing the electrostatic interactions between the porphyrin bulky terminal groups in the SAM, n-C₅H₁₁PO₃H₂ and n-C₁₀H₂₁PO₃H₂ were used to form mixed monolayers with Co-Porph-PO₃H₂ on gold. Intermediate electrochemical desorption potentials regarding those values of pure monolayers, as well as an increase of phosphonate surface density compared to that of Co-Porph-PO₃H₂ SAM, confirm the presence of two-component SAMs, which indicates that porphyrin moieties are diluted in the monolayer. The electrocatalytic activity of the immobilized molecules was demonstrated towards the reduction of molecular oxygen, in acidic medium.     

Structural,vibrational study and superprotonic behavior of a new mixed dipotassium hydrogenselenate dihydrogenphosphate K2(HSeO4)1.5(H2PO4)0.5

Ongoing studies of the KHSeO₄–KH₂PO₄ system aiming at developing novel proton conducting solids resulted in the new compound K₂(HSeO₄)_1.5(H₂PO₄)_0.5 (dipotassium hydrogenselenate dihydrogenphosphate). The crystals were prepared by a slow evaporation of an aqueous solution at room temperature. The structural properties of the crystals were characterized by single-crystal X-ray analysis: K₂(HSeO₄)_1.5(H₂PO₄)_0.5 (denoted KHSeP) crystallizes in the space group P 1¯ with the lattice parameters: a = 7.417(3) Å, b = 7.668(2) Å, c = 7.744(5) Å, α = 71.59(3)°, β = 87.71(4)° and γ = 86.04(6)°. This structure is characterized by HSeO₄⁻ and disordered (H_xSe/P)O₄⁻ tetrahedra connected to dimers via hydrogen bridges. These dimers are linked and stabilized by additional hydrogen bonds (O–H–O) and hydrogen bridges (O–H…O) to build chains of dimers which are parallel to the [0, 1, 0] direction at the position x = 0.5.The differential scanning calorimetry diagram showed two anomalies at 493 and 563 K. These transitions were also characterized by optical birefringence, impedance and modulus spectroscopy techniques. The conductivity relaxation parameters of the proton conductors in this compound were determined in a wide temperature range. The transport properties in this material are assumed to be due to H⁺ protons hopping mechanism.     

In situ electrochemical STM study of platinum nanodot arrays on highly oriented pyrolythic graphite prepared by electron beam lithography

Model electrodes consisting of platinum dots with a mean diameter of (30 ± 5) nm and heights of 3–5 nm upon highly oriented pyrolytic graphite (HOPG) were prepared by electron beam lithography and subsequent sputtering. The Pt nanodot arrays were stable during scanning tunnelling microscopy (STM) measurements in air and in sulphuric acid electrolyte, indicating the presence of “anchors”, immobilising the dots on the HOPG surface.Electrochemical STM was used to visualise potential induced Pt, carbon and Pt-influenced carbon corrosion in situ in 0.5 M sulphuric acid under ambient conditions. Potentiostatic hold experiments show that the Pt dots start to disappear at electrode potentials of E > 1.4 V vs. SHE. With increasing time and potential a hole pattern congruent to the original dot pattern appears on the HOPG basal planes. Corrosion and peeling of the HOPG substrate could also be followed in situ.Dissolution of Pt dots appears to be accelerated for potential cycling experiments compared to the potential hold statistics.     

Kinetics for the reactions of phenyl with methanol and ethanol: Comparison of theory and experiment

The kinetics of the C₆H₅ reactions with CH₃OH and C₂H₅OH has been measured by pulsed-laser photolysis/mass-spectrometry (PLP/MS) employing acetophenone as the radical source. Kinetic modeling of the benzene formed in the reactions over the temperature range 306–771 K allows us to reliably determine the total rate constants for H-abstraction reactions. In order to improve our low temperature measurements down to 304 K we have also applied the cavity ring-down spectrometric technique using nitrosobenzene as the radical source. Both sets of data agree closely. A weighted least-squares analysis of the two complementary sets of data for the two reactions gave the total rate constants k(CH₃OH) = (7.82 ± 0.44) × 10¹¹ exp [?(853 ± 30)/T] and k(C₂H₅OH) = (5.73 ± 0.58) × 10¹¹ exp [?(1103 ± 44)/T] cm³ mol^?1 s^?1 for the temperature range studied. Theoretically, four possible product channels of the C₆H₅ + CH₃OH reaction producing C₆H₆ + CH₃O, C₆H₆ + CH₂OH, C₆H₅OH + CH₃ and C₆H₅OCH₃ + H and five possible product channels of the C₆H₅ + C₂H₅OH reaction producing C₆H₆ + C₂H₅O, C₆H₆ + CH₂CH₂OH, C₆H₆ + CH₃CHOH, C₆H₅OH + CH₃CH₂ and C₆H₅OCH₂CH₃ + H have been computed at the G2M//B3LYP/6?311+G(d, p) level of theory. The hydrogen abstraction channels were predicted to have lower energy barriers than those for the substitution reactions and their rate constants were calculated by the microcanonical variational transition state theory at 200–3000 K. The predicted rate constants are in good agreement with the experimental values. Significantly, the rate constant for the CH₃OH reaction with C₆H₅ was found to be greater than that for the C₂H₅OH reaction and both reactions were found computationally to be dominated by H-abstraction from the hydroxyl group attributable to the affinity of the phenyl toward the OH group and the predicted lower energy barriers for the OH attack.     

Multi-species time-history measurements during n-hexadecane oxidation behind reflected shock waves

Species concentration time-histories were measured during oxidation for the large, normal-alkane, diesel-surrogate component n-hexadecane. Measurements were performed behind reflected shock waves in an aerosol shock tube, which allowed for high fuel loading without pre-test heating and possible decomposition and oxidation. Experiments were conducted using near-stoichiometric mixtures of n-hexadecane and 4% oxygen in argon at temperatures of 1165–1352 K and pressures near 2 atm. Concentration time-histories were recorded for five species: C₂H₄, CH₄, OH, CO₂, and H₂O. Methane was monitored using DFG laser absorption near 3.4 μm; OH was monitored using UV laser absorption at 306.5 nm; C₂H₄ was monitored using a CO₂ gas laser at 10.5 μm; and CO₂ and H₂O were monitored using tunable DFB diode laser absorption at 2.7 and 2.5 μm, respectively. These time-histories provide critically needed kinetic targets to test and refine large reaction mechanisms. Comparisons were made with the predictions of two diesel-surrogate reaction mechanisms (Westbrook et al. [1]; Ranzi et al. [9]) that include n-hexadecane, and areas of needed improvement in the mechanisms were identified. Comparisons of the intermediate product yields of ethylene for n-hexadecane with those found for other smaller n-alkanes, show that an n-hexadecane mechanism derived from a simple hierarchical extrapolation from a smaller n-alkane mechanism does not properly simulate the experimental measurements.     

New optoelectronic materials: Effects of annealing upon the formation of epitaxial iron silicide nanostructures on Si(001)

Iron silicide nanostructures were grown on Si(001) by a strain-induced, self-assembly method. 1 nm iron was deposited by electron gun evaporation and subsequently annealed at 850 °C for different times, between 10 and 50 min. The formation of nanostructures was traced by reflection high energy electron diffraction, and the formed nanoobjects were characterized by scanning electron microscopy and atomic force microscopy. The electrical features were measured by I–V, C–V, deep level transient spectroscopy and conductive atomic force microscopy. As a function of the annealing time the size and the shape of the iron silicide nanoobjects varied, while they were orientated in normal directions. With the rising duration of annealing time the height of the nanostructures emerged, with moderate lateral size enhancement. The electrical characterization shows that the Fe-related defects dominated in all samples in a depth below the surface depending on the time of annealing. These defects are closer to the conduction band at the beginning of the annealing, and after 30 min their concentration is much reduced and they are closer to the valence band.     

An experimental and modeling study of the shock tube ignition of a mixture of n-heptane and n-propylbenzene as a surrogate for a large alkyl benzene

Alkyl aromatics are an important chemical class in gasoline, jet and diesel fuels. In the present work, an n-propylbenzene and n-heptane mixture is studied as a possible surrogate for large alkyl benzenes contained in diesel fuels. To evaluate it as a surrogate, ignition delay times have been measured in a heated high pressure shock tube (HPST) for a mixture of 57% n-propylbenzene/43% n-heptane in air (≈21% O₂, ≈79% N₂) at equivalence ratios of 0.29, 0.49, 0.98 and 1.95 and compressed pressures of 1, 10 and 30 atm over a temperature range of 1000–1600 K. The effects of reflected-shock pressure and equivalence ratio on ignition delay time were determined and common trends highlighted. A combined n-propylbenzene and n-heptane reaction mechanism was assembled and simulations of the shock tube experiments were carried out. The simulation results showed very good agreement with the experimental data for ignition delay times. Sensitivity and reaction pathway analyses have been performed to reveal the important reactions responsible for fuel oxidation under the shock tube conditions studied. It was found that at 1000 K, the main consumption pathways for n-propylbenzene are abstraction reactions on the alkyl chain, with particular selectivity to the allylic site. In comparison at 1500 K, the unimolecular decomposition of the fuel is the main consumption pathway.     

Electron-energy-loss spectroscopy of C60 monolayer films on active and inactive surfaces

The characteristics of interaction between C₆₀ molecules and Si(1 1 1)-7×7, Ag/Si(1 1 1)-√3×√3 R30° and layered material MoS₂ surfaces have been investigated using electron-energy-loss spectroscopy (EELS). The EEL spectrum of C₆₀/Si(1 1 1)-7×7 shows a new peak at loss energy of 2.7 eV. This indicates the existence of charge transfer from the substrate to C₆₀ molecules. The EEL spectrum of a C₆₀ monolayer film grown on a cleaved surface of MoS₂ is almost the same as that of bulk C₆₀. The EEL spectrum of a C₆₀ monolayer film on an Ag/Si(1 1 1) surface is quite different from that on a clean Si(1 1 1)-7×7 surface, although the films on those substrates have the same epitaxial arrangement. Furthermore, intensities of energy-loss peaks of C₆₀/Ag/Si(1 1 1) are slightly smaller than those of C₆₀/MoS₂ in spite of having the same loss-energy. This suggests that the interaction between C₆₀ molecules and the Ag/Si(1 1 1) surface is stronger than that between C₆₀ molecules and the MoS₂ surface.     

The thermodynamic and kinetic properties of hydrogen dimers on graphene

The thermodynamic and kinetic properties of hydrogen adatoms on graphene are important to the materials and devices based on hydrogenated graphene. Hydrogen dimers on graphene with coverages varying from 0.040 to 0.111 ML (1.0 ML = 3.8 × 10¹⁵cm^? 2) were considered in this report. The thermodynamic and kinetic properties of H, D and T dimers were studied by ab initio simulations. The vibrational zero-point energy corrections were found to be not negligible in kinetics, varying from 0.038 (0.028, 0.017) to 0.257 (0.187, 0.157) eV for H (D, T) dimers. The isotope effect exhibits as that the kinetic mobility of a hydrogen dimer decreases with increasing the hydrogen mass. The simulated thermal desorption spectra with the heating rate α = 1.0 K/s were quite close to experimental measurements. The effect of the interaction between hydrogen dimers on their thermodynamic and kinetic properties was analyzed in detail.