Adsorption of acetylene and ethylene on a clean Ir(111) surface

The adsorption of C₂H₂ and C₂H₄ on Ir(111) is studied within the temperature range 180–500 K by the HREELS and XPS methods. The absolute concentration of hydrocarbon coverage is estimated by XPS. Data are obtained on the kinetics of adsorption of the two gases at different temperatures. It is established by HREELS studies that at 180 K C₂H₄ forms ethylidyne (CCH₃ whereas C₂H₂ is adsorbed as CCH and ethylidyne species. At 300 K both kinds of species are found on the Ir(111) surface after C₂H₂ or C₂H₄ exposures. The ethylidyne decomposes completely to CCH at 500 K, which can be accompanied by polymerization of adsorbed hydrocarbon species.     

A study of the relative brönsted acidities of surface complexes on Ag(110)

The relative acidities of a number of Brönsted acids have been established on the Ag(110) surface under UHV conditions. For acids which react completely with adsorbed oxygen atoms on this surface to form H₂O, relative acidities were determined by means of acid-base titration reactions. Adsorbed species such as carboxylates, alkoxides, etc., were formed by reaction of the parent acids with O(a) and then displaced from the surface by titration with stronger acids. Relative acidities of the acids which did not react to completion with O(a) were established on the basis of their relative extents of reaction. The relative acidity scale on Ag(110), according to the reaction BH(g) + B'(a) B'H(g) + B(a) was found to be HCOOH ≈ CH₃COOH>C₂H₅OH> C₂H₂>CH₃OH>C₃H₆, H₂O>C₂H₄, C₂H₆, H₂. This order is in excellent agreement with the acidity scale for these species in the gas phase according to BH(g)B^?(g) + H⁺ (g); it cannot be explained by aqueous dissociation constants or homolytic bond dissociation energies. This result is in accord with the appreciable anionic character of the adsorbed species, since the electron affinity of the base, B, is a strong thermodynamic factor in the acidity in the gas phase. Both XPS and UPS results for adsorbed species on the Ag(110) surface are consistent with this interpretation.     

Penning ionization electron spectroscopy of molecular adsorbates on Pd and Cu surfaces

The electronic properties of CO, PF₃, NH₃, C₂H₂ and C₆H₆ adsorbed on Pd(111), Pd(110), and Cu(110) surfaces were studied by Auger deexcitation (AD) of metastable noble gas atoms (Penning ionization) and by ultraviolet photoelectron spectroscopy (UPS). Electron emission via AD is restricted to the outmost levels localized at the adsorbed particles. The AD process competes with reasonance ionization of the metastable atoms, and its probability depends on the geometry of the adsorbed species and on its adsorption sites as well as on coverage. The differences in kinetic energy of electrons emitted by AD or by photons reflect modifications of the electron affinities of the adsorbed molecules. The extreme surface sensitivity of AD spectroscopy allows in particular to probe the local density of states at the adsorbate in the energy range close to the Fermi level which arises from π “back donation” as well as σ antibonding contributions.     

Interaction of O2, CO2, CO,C2H4 and C2H4O with Ag(110)

The interaction of O₂, CO₂, CO, C₂H₄ AND C₂H₄O with Ag(110) has been studied by low energy electron diffraction (LEED), temperature programmed desorption (TPD) and electron energy loss spectroscopy (EELS). For adsorbed oxygen the EELS and TPD signals are measured as a function of coverage (θ). Up to θ = 0.25 the EELS signal is proportional to coverage; above 0.25 evidence is found for dipole-dipole interaction as the EELS signal is no longer proportional to coverage. The TPD signal is not directly proportional to the oxygen coverage, which is explained by diffusion of part of the adsorbed oxygen into the bulk. Oxygen has been adsorbed both at pressures of less than 10^-4 Pa in an ultrahigh vacuum chamber and at pressures up to 10³ Pa in a preparation chamber. After desorption at 10³ Pa a new type of weakly bound subsurface oxygen is identified, which can be transferred to the surface by heating the crystal to 470 K. CO₂ is not adsorbed as such on clean silver at 300 K. However, it is adsorbed in the form of a carbonate ion if the surface is first exposed to oxygen. If the crystal is heated this complex decomposes into O_ad and CO₂ with an activation energy of 27 kcal/mol(1 kcal = 4.187 kJ). Up to an oxygen coverage of 0.25 one CO₂ molecule is adsorbed per two oxygen atoms on the surface. At higher oxygen coverages the amount of CO₂ adsorbed becomes smaller. CO readily reacts with O_ad at room temperature to form CO₂. This reaction has been used to measure the number of O atoms present on the surface at 300 K relative to the amount of CO₂ that is adsorbed at 300 K by the formation of a carbonate ion. Weakly bound subsurface oxygen does not react with CO at 300 K. Adsorption of C₂H₄O at 110 K is promoted by the presence of atomic oxygen. The activation energy for desorption of C₂H₄O from clean silver is ～ 9 kcal/mol, whereas on the oxygen-precovered surface two states are found with activation energies of 8.5 and 12.5 kcal/mol. The results are discussed in terms of the mechanism of ethylene epoxidation over unpromoted and unmoderated silver.     

C2H4在清洁和有Cs覆盖的Ru(0001)表面吸附的TDS研究

用热脱附谱(TDS)方法研究了乙烯(C₂H₄)在Ru(0001)表面上的吸附.在低温下(200K以下)乙烯可以在清洁及有Cs的Ru(0001)表面上以分子状态稳定吸附,在衬底温度升高至200K以上时,乙烯发生了脱氢分解反应,乙烯分解后的主要产物为乙炔(C₂H₂).在清洁的Ru(0001)表面,乙烯有两种吸附状态,脱附温度分别为275K和360K.而乙炔的脱附温度为350K.在Ru(0001)表面有Cs的存在时,乙烯分解 关键词： 乙烯 钌(0001)表面 铯钌(0001)表面乙烯 钌(0001)表面 铯钌(0001)表面     

Raman spectra of molecules considered to be surface enhanced

High resolution electron energy loss spectroscopy (HREELS) and low energy electron diffraction (LEED) have been used to study the structure of adsorbed benzene (C₆H₆ and C₆D₆) monolayers on the Rh(111) surface at 300K. A surface bonding geometry is proposed for benzene adsorbed to give a c(2?3×4) rectangular structure, which involves very little perturbation of the molecular structure with the ring plane parallel to the surface. Only one chemical environment for adsorbed benzene is indicated by a single frequency shift of the symmetric CH out-of-plane bending mode. The adsorption site is tentatively assigned to benzene centered over a single Rh atom.     

Vibrational spectra of ethylene and acetylene on metal surfaces - an electron energy loss study of ethylene adsorbed on Ni(110) and its carbided surface,and the use of metal-cluster analogies

An analysis has been made of on- and off-specular electron energy loss spectra (EELS) from C₂H₄ and C₂D₄ adsorbed on a clean Ni(110) and also a carbided Ni(110) surface. The carbided surface was prepared by heating the clean Ni surface in ethylene to 573 K or above. EELS spectra were obtained using a Leybold-Heraeus spectrometer at a beam energy of 3.0 eV and with a resolution of ca. 6.5 meV (ca. 50 cm^?1).The loss spectrum from ethylene at low temperatures (110 K) showed principal features at 3000 (w), 1468 (w), 1162 (s), 879 (w) and 403 cm^?1 (s) (C₂D₄ adsorption) and 2186 (w), 1258 (ms), 944 (ms), 645 (w) and 400 cm^?1 (s) (C₂D₄ adsorption). The overall pattern of wavenumbers and intensifies of the C₂H₄/C₂D₄ loss peaks is very similar in form (although systematically different in positions) to those previously observed on Ni(111) (ref.1) and Pt(111) (ref.2) surfaces at low temperatures. Like these earlier spectra,the EELS results for C₂H₄/C₂D₄ adsorbed on clean Ni(110) can be well interpreted in terms of a MCH₂CH₂M/MCD₂CD₂M species (M = metal) with the CC bond parallel to the surface.After adsorption on the carbided Ni(110) surfaces at 125 K,the main loss features occur at 3065 (m), 2992 (m), 1524 (ms), 1250 (s), 895 (s), and 314 cm^?1 (vs) (C₂H₄ adsorption) and 2339 (m), 2242 (m), 1395 (s), 968 (s), 661 (m) and 314 cm^?1 (vs). With the exceptions of reduced intensities of the bands at 895 cm^?1 (C₂H₄) and 661 cm^?1 (C₂D₄) this pattern of losses - particularly the 1550-1200 cm^?1 features which can be assigned to coupled νCC and δCH₂/δCD₂ modes - is well related to similar results on Cu(100) (ref.3) and Pd(111) (ref.4) which have been interpreted convincingly in terms of the presence of π-bonded species, (C₂H₄)M or (C₂D₄)M on the surface. This structural assignment is supported by comparison with the vibrational spectra of Zeise's salt, K[PtCl₃(C₂H₄)].H₂O (refs.5&6).Spectral changes occur on warming C₂H₄ on the clean Ni(110) surface with a growth of a feature near 895 cm^?1 at 200 K. At 300 K a rather poorly-defined spectrum occurs, which differs substantially from those found on (111) surfaces of Pt (ref.2), Rh (ref.7) or Pd (ref.8) at room temperature. These latter have been attributed to the ethylidyne, CH₃.CM₃, surface species (ref.9). For adsorption on Ni(110) there is clearly a mixture of species at room temperature.The analysis of the vibrational spectra of selected metal-cluster compounds of known structure with selected hydrocarbon ligands has helped substantially to assign the spectra of surface species in terms of bonding structures of the adsorbed species, as in the cases of the identification of (C₂H₄)M π-adsorbed (refs.5&6) and the ethylidyne CH₃.CM₃ species (ref.9). We have recently analysed the infrared and Raman spectra of the cluster compound (C₂H₂)Os₃(CO)₁₀ and its deuterium-containing analogue. The infrared frequency and intensity pattern for the A′ modes (C_S symmetry) of the two isotopomers bears a remarkable resemblance to EELS spectra previously obtained at low temperature for C₂H₂/C₂D₂ adsorbed on Pt(111) (ref.2) and (after taking into account systematic frequency shifts) for Pd(111) (ref.4). There is good evidence for believing that the structure of the hydrocarbon ligand interacting with the osmium complex takes the form

where the arrow denotes a π-bond to the third metal atom. This strongly confirms the structure for the low-temperature acetylene species on Pt(111) as proposed by Ibach and Lehwald (ref.2).Finally the room-temperature spectra for ethylene adsorbed on finely-divided silica-supported Pt and Pd catalysts have previously been interpreted in terms of the presence of MCH₂CH₂M (ref.10) and π-bonded (C₂H₄)M species (ref.11). However comparisons with the more recent EELS spectra from ethylene on Pt(111) at room temperature (ref.2) now leads to a reassignment of the 2880 cm^?1 band, on Pt, previously assigned to MCH₂CH₂M, together with a new, related,band at 1340 cm^?1 (ref.12), to the ethylidyne species CH₃CPt₃ found on the single crystal surface.More detailed analyses of the spectra reported here will be published later. Acknowledgement is given to substantial assistance for this programme of research from the Science and Engineering Research Council.     

A HREELS study of the UV photon-induced chemistry of C6H5Cl adsorbed on Ag{111}

The UV photochemistry of both monolayer and multilayer C₆H₅Cl adsorbed on Ag{111} surfaces has been studied using high resolution electron energy loss spectroscopy (HREELS). Photon-induced dissociation via the cleavage of the CCl bonds was observed as a common feature. For the monolayer, chemisorbed biphenyl appears to be formed on the surface after photolysis at 110 K and subsequent annealing to 300 K. The two phenyl rings are found to lie parallel to the metal surface. The photon-induced dissociation of multilayer C₆H₅Cl leads, however, to photopolymerization as shown by the high thermal stability of the surface species formed and the detection of simple additive products in thermal desorption.     

EFFECT OF ATOMIC HYDROGEN ON THE ACETYLENE-ADSORBED Si(100)(2×1) SURFACE AT ROOM TEMPERATURE

High resolution electron energy loss spectroscopy, low energy electron diffraction and quadrupole maas spectrometer (QMS) have been employed to study the effect of atomic hydrogen on the acetylene-saturated pre-adsorbed Si(100)(2×1) surface and the surface phase transition at room temperature. It is evident that the atomic hydrogen has a strong effect on the adsorbed C₂H₂ and the underlying surface structure of Si. The experimental results show that CH and CH₂ radicals co-exist on the Si surface after the dosing of atomic hydrogen; meanwhile, the surface structure changes from Si(100)(2×1) to a dominant of (1×1). These results indicate that the atomic hydrogen can open C=C double bonds and change them into C-C single bonds, transfer the adsorbed C₂H₂ to C₂H_x(x = 3,4) and break the underlying Si-Si dimer, but it cannot break the C-C bond intensively. The QMS results show that some C₄ species axe formed during the dosing of atomic hydrogen. It may be the result of atomic hydrogen abstraction from C₂H_x which leads to carbon catenation between two adjacent C-C directs. The C₄ species formed are stable on Si(100) surfaces up to 1100 K, and can be regarded as the potential host of diamond nucleation.     

Neutron inelastic spectroscopy of benzene chemisorbed on Raney platinum

The neutron inelastic scattering spectrum of benzene adsorbed at 300 K on Raney platinum has been measured between 350 and 2250 cm^?1. No deshydrogenation of the molecules is observed so that the benzene ring must be adsorbed parallel to the surface. Slight modifications of the force field of the model molecule (C₆H₆)Cr(CO)₃ were introduced to account for the vibrational frequency shifts. The benzene molecule is found less perturbed on platinum than on nickel. The calculated frequencies of adsorbed C₆H₆ and C₆D₆ are used to reassign some modes previously observed by electron loss spectroscopy.     

Adsorption-desorption studies using ESD of CCl2F2, C2H2F2 and C2F6 on tungsten

The behavior of the desorbing F⁺ ion current from electron bombarded CCl₂F₂, C₂H₂F₂ and C₂F₆ adsorbed on tungsten has been used to investigate the processes of adsorption and desorption of these gases. For tungsten near room temperature, measurements of the F⁺ ion current as a function of electron bombardment time indicated very similar or even identical F⁺-yielding adsorbed species resulting from adsorption of either CCl₂F₂ or C₂H₂F₂ and widely different species from C₂F₆. Cl⁺ ions were also observed to desorb from CCl₂F₂ ad-layers. The behavior of the Cl⁺ ion current with time during electron bombardment indicated electronic conversion between adsorbed binding modes. Complementary investigations on the interaction of CCl₂F₂, C₂H₂F₂ and C₂F₆ with tungsten were carried out by thermal desorption experiments in which the F⁺ ion signal was used to observe the coverage decrease of the F⁺-yielding species. The experiments were performed at tungsten temperatures in the 1200–1600 K range. It was concluded that the F⁺-yielding adsorbed species from CCl₂F₂ and C₂H₂F₂ were strongly bound to the tungsten surface. The F⁺-yielding species from C₂F₆ were found to be weakly bound. From a comparison of the ESD and thermal desorption results, the possibility of dissociative adsorption as well as the nature of the adsorbed species is discussed.     

Leed and thermal desorption studies of small molecules (H2, O2, CO,CO2, NO,C2H4, C2H2 AND C) chemisorbed on the rhodium (111) and (100) surfaces

The chemisorption of H₂, O₂, CO, CO₂, NO, C₂H₄, C₂H₂ and C has been studied on the clean Rh(111) and (100) surfaces. LEED, AES and thermal desorption were used to determine the surface structures, disordering and desorption temperatures, displacement and decomposition characteristics for each species. All of the molecules studied readily chemisorbed on both surfaces. A large variety of ordered structures was observed, especially on the (111) surface. The disordering temperatures of most ordered surface structures on the (111) surface were below 100°C. It was necessary to adsorb the gases at 25° C or below in order to obtain well-ordered surface structures. Chemisorbed oxygen was readily removed from the surface by H₂ or CO gas at crystal temperatures above 50°C. CO₂ appears to dissociate to CO upon adsorption on both rhodium surfaces as indicated by the identical ordering and desorption characteristics of these two molecules. C₂H₄ and C₂H₂ also had very similar ordering and desorption characteristics and it is likely that the adsorbed species formed by both molecules is the same. Decomposition of ethylene produced a sequence of ordered carbon surface structures on the (111) face as a result of a bulk-surface carbon equilibrium. The chemisorption properties of rhodium appear to be generally similar to those of iridium, nickel and palladium.     

Exploring the mechanism of NO–C2H4 reactions on the surface of stepped Pt(3 3 2)

Fourier transform infra red reflection–absorption spectroscopy (FTIR-RAS), thermal desorption spectroscopy (TDS), and auger electron spectroscopy (AES), were employed to explore the mechanism of NO reduction in the presence of C₂H₄ on the surface of stepped Pt(3 3 2). Both NO–Pt and C₂H₄–Pt interactions are enhanced when NO and C₂H₄ are co-adsorbed on Pt(3 3 2). As a result, C₂H₄ is dissociated at surface temperatures as low as 150 K, and the N–O stretch band is weakened. The presence of post-exposed C₂H₄ leads NO desorption from steps to decrease significantly, but the same effect on NO desorption from terraces becomes appreciable only at higher post-exposures of C₂H₄, e.g., 0.6 L and 1.2 L, and proceeds to a much slighter extent. Auger spectra indicate that as a result of the reaction with O from NO dissociation, the amount of surface C species is greatly reduced when NO is post-exposed to a C₂H₄ adlayer. It is concluded that reduction of NO in the presence of C₂H₄ proceeds very effectively on the surface of the Pt(3 3 2), through a mechanism of NO dissociation and subsequent O removal. Following this mechanism, the significant dissociation of adsorbed NO molecules on steps at surface temperatures below 400 K, and subsequent rapid reaction between the resultant O and C-related species, accounts for the considerable amount of N₂ desorption at temperatures below 400 K.     

Effects of subsurface Na,H and C on the bonding of carbon to nickel surfaces

This paper reports the results of a theoretical study of Na, H and C subsurface atomic species in nickel and demonstrates how these interstitial atoms influence the reactivity of the Ni(111) surface and the structure of carbon species adsorbed on the surface. The benzene molecule, C₆H₆, in planar and nonplanar geometries, is used to probe bonding at the surface. Adsorption energies are calculated by ab initio configuration interaction techniques modelling the surface as an embedded cluster. Adsorption energies of planar C₆H₆ at the most stable, three-fold, adsorption site are 18 kcal/mol for the Ni(111) surface, and 10, 19 and 44 kcal/mol in the presence of the Na, H and C interstitials, respectively. The energies required for the planar to puckered distortion are 99 kcal/mol on Ni(111), 69 kcal/mol with the Na interstitial, 83 kcal/mol with H, and 134 kcal/mol with C compared to 198 kcal/mol for distortion of C₆H₆ in the gas phase. The possible relevance of these results to the nucleation of diamond on nickel are discussed. The results indicate that subsurface Na stabilizes tetrahedrally bonded carbon subunits of the diamond structure while subsurface C may make it easier for the overlayer to revert to a planar graphite structure.     

Ethylene adsorption on thin films of Ni,Pd, Pt,Cu, Au and Al; Work function measurements

The changes in work function φ upon adsorption of C₂H₄ on clean film surfaces of six fcc metals (Ni, Pd, Pt, Cu, Au and Al) have been followed by means of photoelectron emission at 293 K. A marked difference was observed in the behaviour between Ni, Pd and Al on the one side and on Cu, Au and Pt on the other side: while with Ni, Pd and Al, φ as a function of coverage goes through a maximum, with Cu, Au and Pt, φ only decreases. In the discussion, the data obtained by work function measurements are related to other literature data. Several films covered with C₂H₄species were also submitted to a heat treatment while in other experiments H₂ was admitted to the surface covered by C₂H₄ species. In some experiments C₂h₄ was admitted to surfaces covered by H₂. In all cases φ was measured. The experiments reveal that C₂h₄is absorbed only reversibly on Cu and Au. On Ni, Pd and Pt, C₂H₄ is adsorbed initially with dissociation and this leads to an increase in φ on Ni and Pd and a decrease on Pt. Hydrogenated reactive species contribute to the lowering of φ observed with Ni, Pd and Pt. As with Cu and Au also on Ni, Pd and Pt a weakly bound C₂h₄is observed which leads to a decrease in φ as well. The behaviour of φ indicates that upon Al, C₂h₄ adsorbs first dissociatively to a small extent, while the weakly bound C₂H₄species act as intermediates for strongly adsorbed species which were observed after some time.     

Photoemission studies of H2S,H2 and S adsorbed on Ru(110): Evidence for an adsorbed SH species

H₂S, H₂ and S adsorbed on Ru(110) have been studied by angle-integrated ultraviolet photoemission (UPS) as part of a study of the effect of adsorbed sulfur, a common catalytic poison, on this Ru surface. For low exposures of H₂S at 80 K, the work function rises to a value 0.16 eV above that of clean Ru(110) while the associated UPS spectra (hν = 21.2 eV) exhibit features similar to those of H(ads) and S(ads) and different from those of molecular H₂S. We conclude that H₂S dissociates completely at low coverages on Ru(110) at 80 K. At intermediate exposures the work function drops and the UPS spectra show new features which are attributed to the presence of an adsorbed SH species. This appears to be the first direct observation of this surface complex. At higher exposures the work function saturates at a value 0.36 eV below the clean value; the UPS spectra change markedly and indicate the adsorption of molecular H₂S. Heating adsorbed H₂S leaves a stable layer of S(ads) on Ru(110). The surface with adsorbed sulfur strongly modifies the adsorption at 80 K of a number of molecules relative to the clean Ru(110) surface.     

An EELS and TPD study of the adsorption and decomposition of acetic acid on the Al(111) surface

The adsorption and decomposition of acetic acid on Al(111) have been studied using electron energy loss spectroscopy (EELS), temperature programmed desorption (TPD), and Auger electron spectroscopy (AES). Acetic acid reacts with clean Al(111) at 120 K to form a surface acetate species. The adsorbed acetate bonds to the surface in a symmetric configuration with C_s symmetry at 120 K. The adsorption of molecular acetic acid occurs at this temperature only after saturation of the surface acetate layer; this physisorbed multilayer desorbs molecularly at 167 K. Thermal decomposition of the adsorbed acetate leads to a carbon- and oxygen-covered surface; the only detectable thermal decomposition product is H₂. Electron irradiation induces a similar decomposition process of the surface acetate.     

The direct molecular orbital dynamics study on the hydrogen species adsorbed on the surface of planar graphite cluster model

In order to investigate thermal behaviors of the hydrogen species, H⁺ ion and H atom, adsorbed on the surface of planar graphite, the direct molecular orbital dynamics (MO) calculations at AM1 level are applied to the hydrogen terminated planar cluster models included by the species, C₅₄H₁₈·H⁺ and C₅₄H₁₈·H, respectively. This is the first trial to describe the thermal behaviors of these species in terms of MO dynamics. Both hydrogen species form the covalent bonds with the surface carbon atoms through the sp³ hybrid orbitals which inhibit their dissociation at high temperature up to 2000 K. It was found that the reduction of band gap is introduced by the adsorption of H⁺ ion.     

Adsorption and decomposition of H2O on a K-covered Pt(111) surface

The adsorption of H₂O on clean and K-covered Pt(111) was investigated by utilizing Auger, X-ray and ultra-violet photoemission spectroscopies. The adsorption on Pt(111) at 100–150 K was purely molecular (ice formation) in agreement with previous work. No dissociation of this adsorbed H₂O was noted on heating to higher temperatures. On the other hand, adsorption of H₂O on Pt(111) + K leads to dissociation and to the formation of OH species which were characterized by a work function increase, an O 1s binding energy of 530.9 eV and UPS peaks at 4.7 and 8.7 eV below the Fermi level. The amount of OH formed was proportional to the K coverage for θ_K > 0.06 whereas no OH could be detected for θ? 0.06. Dissociation of H₂O occurred already at T = 100 K, with a sequential appearance of O 1s peaks at 531 and 533 eV representing OH and adsorbed H₂O, respectively. At room temperature and above only the OH species was observed. Annealing of the surface covered with coadsorbed K/OH indicated the high stability of this OH species which could be detected spectroscopically up to 570 K. The adsorption energy of H₂O coadsorbed with K and OH on Pt(111) is increased relative to that of H₂O on Pt. The work function due to this adsorbed H₂O increases whereas it decreases for H₂O on Pt(111). The energy shifts of valence and O1s core levels of H₂O on Pt + K as deduced from a comparison of gas phase and adsorbate spectra are 2.8–4.2 eV compared to ≈ 1.3–2.3 eV for H₂O on Pt (111). This increased relaxation energy shift suggests a charge transfer screening process for H₂O on Pt + K possibly involving the unoccupied 4a₁ orbital of H₂O. The occurrence of this mode of screening would be consistent with the higher adsorption energy of H₂O on Pt + K and with its high propensity to dissociate into OH and H.     

An inelastic neutron scattering study of C2H2 adsorbed on type 13X zeolites

The inelastic neutron scattering spectra of C₂H₂ and C₂D₂ adsorbed on a Ag⁺ exchanged 13X zeolite (0–800 cm^?1) and of C₂H₂ on the Na⁺ form (0–300 cm^?1) have been obtained. For the Na-13X system no distinct vibrational modes were observed, however for the Ag-13X systems the low frequency intramolecular modes of the adsorbed gas and some of the vibrations of the adsorbed gas relative to the surface have been assigned. From the deuteration shifts it appears that C₂H₂ and C₂D₂, adsorbed on Ag-13X, are non-linear.