Showing papers in "Journal of the Chemical Society, Faraday Transactions in 1973"
TL;DR: In this paper, the effect of chloride ions on the mechanism of the Fricke dosimeter is discussed, and the absorption spectra of ClOH and ClOH-2 have been measured in the range 230-450 nm.
Abstract: In aqueous solution OH radicals react with chloride ions to form initially ClOH–, the rate constant being 4.3 ± 0.4 × 109 l. mol–1 s–1. The rate constant for the dissociation of ClOH– back to OH radicals and chloride ions is 6.1 ± 0.8 × 109 s–1. ClOH– is converted to chlorine atoms via the reaction, ClOH–+ H+→ Cl + H2O (k= 2.1 ± 0.7 × 1010 l. mol–1 s–1 at an ionic strength of unity), the rate constant for the reverse reaction being 1.3 × 103 l. mol–1 s–1(0.3–3.0 × 103 l. mol–1 s–1). Chlorine atoms combine with chloride ions to form Cl–2(k= 2.1 × 1010 l. mol–1 s–1), the rate constant for the dissociation of Cl–2 back to chlorine atoms and chloride ions being 1.1 ± 0.4 × 105 s–1.The absorption spectra of ClOH– and Cl–2 have been measured in the range 230–450 nm. Cl–2 absorption has a maximum at 340 nm where the extinction coefficient is 8.8 ± 0.5 × 103 l. mol–1 cm–1, whereas ClOH– has a maximum at 350 nm with an extinction coefficient of 3.7 ± 0.4 × 103 l. mol–1 cm–1.The reactions of chlorine atoms and Cl–2 with ferrous ions have also been investigated and the constants are 5.9 ± 0.6 × 109 and 1.4 ± 0.2 × 107 l. mol–1 s–1(ionic strength = 0.1 mol l.–1) respectively. The effect of chloride ions on the mechanism of the Fricke dosimeter is discussed.
553 citations
TL;DR: In this article, the absorption characteristics and acid dissociation constants of the semiquinone radicals of several methyl derivatives of benzoquinone and naphthoquinone have been determined by pulse radiolysis.
Abstract: The absorption characteristics and acid dissociation constants of the semiquinone radicals of several methyl derivatives of benzoquinone and naphthoquinone have been determined by pulse radiolysis.Absolute rate constants for electron transfer from the superoxide-ion O–2 to mono- and di-methyl benzoquinones have been determined. In the case of duroquinone, evidence has been obtained for the occurrence of the equilibrium reaction: O–2+ duroquinone ⇌ O2+ durosemiquinone with Kc= 2.3 ± 0.2 × 10–2.
304 citations
TL;DR: In this paper, the rate constants for oxygen quenching of aromatic hydrocarbon triplets have been measured by the laser flash photolysis technique, and the importance of restrictive Franck-Condon factors which are determined by the hydrocarbon is discussed.
Abstract: The rate constants for oxygen quenching of aromatic hydrocarbon triplets have been measured by the laser flash photolysis technique. The quenching of high triplet energy compounds is characterised by rates which are inversely proportional to triplet energy. The reaction probabilities, which are as small as 10–2 in hexane, have been found to increase in polar or viscous solvents. Molecules with low triplet energies are quenched at one-ninth the measured diffusion controlled encounter rate.These data are analysed in terms of the non-radiative transitions of a collision complex of the aromatic triplet and ground state oxygen. The importance of restrictive Franck–Condon factors which are determined by the hydrocarbon is discussed. The data are shown to be consistent with electronic matrix elements for the energy transfer quenching processes that are dependent on orbital symmetry matching and charge transfer interactions.
221 citations
TL;DR: In this article, the ionization potentials of substituted thiophens as donors with tetracyanothylene, 2,3-dichloro-5,6-dicyano-p-benzoquinone, chloranil and iodine have been studied spectrophotometrically.
Abstract: Charge transfer complexes of substituted thiophens as donors with tetracyanothylene, 2,3-dichloro-5,6-dicyano-p-benzoquinone, chloranil and iodine have been studied spectrophotometrically. From the energies of the charge transfer transitions, the ionization potentials of the donors have been obtained. Comparison with those measured by electron-impact mass spectrometry, shows that the thiophens behave as π donors with all four acceptors. In the case of iodine the stability constants of the complexes support a π→σ* interaction. Some evidence is given for the role of inner valence orbitals in the complexes.
190 citations
TL;DR: In this paper, the rate of collection of Brownian particles under the influence of interaction forces between the collector surface and the particles is calculated by incorporating the interaction forces in the rate constant of a virtual, first order, chemical reaction taking place on the surface of the collector, and by solving the convective diffusion equation subject to that chemical reaction as a boundary condition.
Abstract: The rate of collection of Brownian particles under the influence of interaction forces between the collector surface and the particles is calculated by (a) incorporating the interaction forces in the rate constant of a virtual, first order, chemical reaction taking place on the surface of the collector, and by (b) solving the convective diffusion equation subject to that chemical reaction as a boundary condition. Several geometries (sphere, cylinder, rotating disc) are considered for the collector.An Arrhenius type equation is obtained for the apparent reaction rate constant. Equations for the apparent activation energy and for the frequency factor are established as functions of Hamaker's constant, ionic strength, surface potentials and particle radius.
189 citations
TL;DR: In this article, the infrared spectra of zeolites X and Y were recorded in the hydroxyl stretching region under high resolution conditions, and the spectra were broken down into six different components.
Abstract: The infrared spectra of zeolites X and Y were recorded in the hydroxyl stretching region under high resolution conditions. The samples varied in their Al and proton content. The spectra were broken down into six different components. The selection of this number of components was based on reproducible details appearing in the high resolution spectra. An assignment for the different components is proposed, which considers the four different types of oxygen ions as possible sites for proton location. The narrow band at 3650 cm–1 is assigned to O1—H hydroxyl groups, while the broad and asymmetric band at 3550 cm–1 contains components due to O2—H, O3—H and O4—H groups.
128 citations
TL;DR: The results of detailed rotational and term-value analyses involving some 7000 lines with 58 levels in B3Π0+u(4 ⩽v⩽ 77) and 6 levels in X1∑+g(0 ⌆⌈v⌆ 5) are given in this paper.
Abstract: The results of detailed rotational and term-value analyses involving some 7000 lines with 58 levels in B3Π0+u(4 ⩽v⩽ 77) and 6 levels in X1∑+g(0 ⩽v⩽ 5) are given. For the B3Π0+u state the rotational constants Bv can be represented by Bv= [graphic omitted]cn(v+½)n, but neither the vibrational levels nor the centrifugal stretching constants follow simple polynomials in (v+½). At high v, ([graphic omitted])10/7 is linear in Ev and a short extrapolation leads to a value of the limit, 20 043.208 ± 0.033 cm–1, relative to X1∑+g(v= 0, J= 0). The highest bound vibrational level has v= 87. An RKR potential energy curve has been calculated for the B3Π0+u state, and a consistent value of the limit, 20 043.220 ± 0.015 cm–1, is obtained from a fit to an attractive part of the curve near the limit, assuming a potential V(r)=–C5/r5–C6/r6–C8/r8. Values of the long-range interaction constants have been obtained: the term in r–6 is not negligible even at internuclear distances as large as 20 A. The ground-state dissociation energy, D0(I2) is found to be 12 440.1 cm–1, corresponding to 35.568 kcal mol–1 or 148.815 kJ mol–1.
127 citations
TL;DR: The dihedral angle between the rings of biphenyl is determined to be 32 ± 2° in the molten and solution states as mentioned in this paper, and the values of the force constants associated with the inter-ring bond are discussed.
Abstract: The dihedral angle between the rings of biphenyl is determined to be 32 ± 2° in the molten and solution states. Observed vibrational frequency shifts on going from the planar configuration held in the crystal to the non-planar solution state are compared with computed frequency shifts. To improve the accuracy in the computed frequencies the force constants were refined. The values of the force constants associated with the inter-ring bond are discussed.
122 citations
TL;DR: In this article, core binding energies of a number of nitrogen bases and their adducts with BF3 are reported, and interpreted using both ab initio and semi-empirical molecular orbital calculations.
Abstract: Core binding energies of a number of nitrogen bases and their adducts with BF3 are reported, and interpreted using both ab initio and semi-empirical molecular orbital calculations. The binding energies are found to reflect the change in molecular charge distribution which occurs on formation of the B—N σ bond. The correlation of the valence molecular orbitals of the complexes with those of the bases and BF3 is discussed.
119 citations
TL;DR: In this article, a general thermodynamic analysis is presented of the influence of adsorption on the force between two solid bodies immersed in a fluid (gas or liquid mixture), one or more of whose components is preferentially adsorbed.
Abstract: A general thermodynamic analysis is presented of the influence of adsorption on the force between two solid bodies immersed in a fluid (gas or liquid mixture), one or more of whose components is preferentially adsorbed. The resulting equations can be applied to the effect of adsorption on the stability of aerosols of solid particles, and of colloidal dispersions of solids in liquids; and to the swelling and shrinking of porous bodies caused by adsorption.The method of calculating interparticle forces, and the potential energies of interaction is illustrated by numerical examples for the case of parallel plates immersed in an adsorptive gas, at pressures in the Henry's law region of the adsorption isotherm. A qualitative discussion is given for adsorption in the multilayer region.
117 citations
TL;DR: In this paper, a simple p-π interaction scheme for amino- and oxy-benzenes was proposed and shown to be effective for the NN-dialkylanilines and 2,6-dimethylanisole.
Abstract: Photoelectron spectroscopic data for amino- and oxy-benzenes are discussed in terms of a simple p-π interaction scheme. Steric hindrance is shown only to be important in ortho substituted NN-dialkylanilines and in 2,6-dimethylanisole. In the nitrogen series there is indication that the N atom is not planar.
TL;DR: In this paper, a low angle light scattering technique for the measurement of absolute coagulation rate constants of monodisperse spherical sols has been developed, and the results were compared with calculated values which incorporate (i) a hydrodynamic correction due to Spielman and Honig et al., (ii) an estimate of the electrostatic repulsion between the particles based on constant potential calculations and electrophoretic measurements and (iii) an estimation of the van der Waals attraction based on the Hamaker theory.
Abstract: A new low angle light scattering technique for the measurement of absolute coagulation rate constants of monodisperse spherical sols has been developed. Measurements have been made on a series of polystyrene latices under both rapid and slow coagulation conditions. The results were compared with calculated values which incorporate (i) a hydrodynamic correction due to Spielman and Honig et al., (ii) an estimate of the electrostatic repulsion between the particles based on constant potential calculations and electrophoretic measurements and (iii) an estimate of the van der Waals attraction based on the Hamaker theory. From the rapid rate measurements (accurate to within ± 13%) the value of the Hamaker constant is expected to lie within the range, 3 × 10–21 to 1.6 × 10–21 J. The slow coagulation results suggest that the van der Waals attraction is salt dependent: in 0.2 M NaCl the measured Hamaker constant is ∼4 × 10–21 J which is the value expected from the classical Hamaker theory, in 0.09 M NaCl agreement between theory and experiment requires this value to have increased to 1.1 × 10–20 J. These findings are in qualitative agreement with the recent theoretical predictions of Parsegian and Ninham which are based on the macroscopic Lifshitz theory of van der Waals interactions.
TL;DR: In this article, the influence of the coupling of the proton movement and the H bond stretching vibration in a double minimum potential energy surface on the energy levels, transitions, induced dipole moments and polarisabilities is calcualted ab initio as a function of an electric field for the H5O+2 system.
Abstract: The influence of the coupling of the proton movement and the H bond stretching vibration in a double minimum potential energy surface on the energy levels, transitions, induced dipole moments and polarisabilities is calcualted ab initio as a function of an electric field for the H5O+2 system. The high polarisability of the hydrogen bonds remains to a large extent unchanged due to the coupling. New types of transitions occur, particularly when the tunnelling frequency and the frequency of the bond stretching vibration are comparable in size. Especially in this case numerous Fermi resonances occur due to the shift of the energy levels in the electric field, which leads to a considerable increase in the number of transitions. It is shown that the change of the frequencies of the transitions due to the induced dipole interaction of the bonds with fields from their environment is a decisive cause of the variety of energy level differences observed as a continuous absorption in the i.r. spectrum of such systems.
TL;DR: In this article, a statistical model based on the quasi-chemical approach of Fowler and Guggenheim is used to derive a kinetic equation for the associative desorption of a heteronuclear diatomic molecule, taking into account the existence of lateral interactions between nearest-neighbour adatoms in the overlayer.
Abstract: Ordered structures formed by the β states of carbon monoxide on single crystal tungsten surfaces imply strong lateral interactions between adatoms. A statistical model, based on the quasi-chemical approach of Fowler and Guggenheim, is used to derive a kinetic equation for the associative desorption of a heteronuclear diatomic molecule, taking into account the existence of lateral interactions between nearest-neighbour adatoms in the overlayer. The model thus provides a link between structural and kinetic studies of chemisorption. It is successfully applied to the β desorption spectra for CO on W reported in Part 1, and a pairwise lateral repulsive interaction energy of 20 kJ mol–1 between C and O adatoms is derived. The kinetic equation is extended to allow for a variation in the C/O adatom ratio, and again the predictions of the model are in close agreement with the experimental CO desorption spectra of Goymour and King from mixed O2+ CO adlayers on W.
TL;DR: Some aspects of the HeI photoelectron spectroscopy of substituted phenylethylenes and related molecules are presented in this article, where the interpretation of the variation of the photo-electron π ionization energies with substituents allows the separation of steric from electronic effects.
Abstract: Some aspects of the HeI photoelectron spectroscopy of substituted phenylethylenes and related molecules are presented. The interpretation of the variation of the photoelectron π ionization energies with substituents allows the separation of steric from electronic effects. Interaction of semi-localised π molecular orbitals incorporated within a Huckel type theory provides a means of estimation of the dihedral angles.
TL;DR: The CO stretching frequency of liquid ethylene and propylene carbonates is higher in the infrared than in the Raman spectrum as mentioned in this paper, which is explained by a coupling between the transition dipoles of neighbouring molecules, made possible by some degree of alignment of molecular dipoles due to the high dipole moment of these molecules.
Abstract: The CO stretching frequency of liquid ethylene and propylene carbonates is higher in the infrared than in the Raman spectrum. The difference amounts to 13 cm–1 for ethylene carbonate at 313 K. This effect is explained as the consequence of a coupling between the transition dipoles of neighbouring molecules, which is made possible by some degree of alignment of molecular dipoles due to the high dipole moment of these molecules (about 16 × 10–30 C m). A study of dilution and temperature effects confirms this interpretation.
TL;DR: In this article, the authors investigated the thermodynamics of association of the positively-charged dye Acridine Orange in water as a function of ionic strength and in the presence of added methanol, urea and dioxan.
Abstract: The thermodynamics of association of the positively-charged dye Acridine Orange have been investigated spectrophotometrically in water as a function of ionic strength and in the presence of added methanol, urea and dioxan. The extinction coefficients IµM, IµD, and IµSt, were measured which are characteristic of the spectra of monomer, dimer and long aggregates of the dye molecules respectively. A theoretical model system, based on short-range stacking and long-range electrostatic interactions, has been used to interpret the thermodynamic data. The results suggest that both factors are of importance in determining the tendency to aggregate. Furthermore, when the solvent is varied they are related by a compensation effect; decreases in stacking interactions are paralleled by decreases in repulsive electrostatic interactions.The results of this study on a model self-associating system are of relevance to the general problem of the importance of stacking and charge effects as factors determining micelle formation, association of nucleotides and nucleosides and the conformational stability of biological macromolecules in solution.
TL;DR: In this article, the half-life of the absorption decay is given by τs=A exp E/RT where log10A= −15.7 and E= 25 kJ (5.9 kcal).
Abstract: The spectra due to electrons in alcohols at temperatures near their melting points show absorptions in the far and infra-red which, in general, decay to produce increased absorptions in the visible. At these temperatures the time for these changes increases in the order methanol, ethanol, n-butyl, isopropyl, n-propyl alcohol. For the latter the half-life of the absorption decay is given by τs=A exp E/RT where log10A=–15.7 and E= 25 kJ (5.9 kcal). Addition of solutes which react with electrons decreases the initial infra-red absorption and is interpreted as reaction with electrons before they become solvated. The observations are discussed in terms of molecular relaxation and electron migration.
TL;DR: In this article, the equilibrium pressures of the Pd/H2 and pd/D2 systems were measured in the temperature range from −100°C to 350°C for values of H(D)-to-Pd, atomic ratio, in the approximate range from 0.0005 to 0.005.
Abstract: The equilibrium pressures of the Pd/H2 and Pd/D2 systems have been measured in the temperature range from –100°C to 350°C for values of H(D)-to-Pd, atomic ratio, in the approximate range from 0.0005 to 0.005. These data were obtained in an ultra-high vacuum apparatus with large samples of low surface area. Partial thermodynamic data have been obtained from these equilibrium data; a significant temperature dependence is reported for the relative partial molar enthalpies and entropies.
TL;DR: Pulse radiolysis of aqueous solutions of formic acid and formate ion in the pH range 0-13 shows that the absorption spectrum of the carboxyl radical is constant between pH 2.5 and 13, but decreases in intensity between pH2.7 and 7.
Abstract: Pulse radiolysis of aqueous solutions of formic acid and formate ion in the pH range 0–13 shows (i) that the absorption spectrum of the carboxyl radical is constant between pH 2.5 and 13, but decreases in intensity between pH 2.5 and 0; (ii) that the effect of ionic strength on the rate of reaction of the radical with itself is the same at pH 2.7 and 7 and is consistent with the radical having unit negative charge at pH 2.7. The data presented indicate that the pK of the radical is 1.4.
TL;DR: In this article, the authors investigated the nature of the oxygen species adsorbed on slightly reduced CeO2/SiO2 supported catalysts using oxygen enriched with 17O2 and found that the observed hyperfine splitting was associated with the central component of the g tensor.
Abstract: The nature of the oxygen species adsorbed on slightly reduced CeO2/SiO2 supported catalysts has been investigated using oxygen enriched with 17O2. The observed hyperfine splitting was found to be associated with the central component of the g tensor; it indicated that the corresponding orbital contained the unpaired electron and therefore the central component was defined as gxx. With this assumption, the e.s.r. spectra are consistent with the adsorption of oxygen as O–2 at 77 K with gyy= 2.0109, gxx= 2.0158 and gzz= 2.028 with a hyperfine splitting (Axx) of 75 G about gxx. The O–2 is adsorbed with the internuclear axis along the surface of the catalyst at a site corresponding to a cerium ion. There is some indication that interaction with the metal ion orbitals is perturbing the energy levels of the adsorbed O–2 ion.
TL;DR: In this paper, the authors used infrared-red spectroscopy of carbon dioxide adsorbed on Na-Ca(Mg)-Y faujasites to determine the distribution of Ca and Mg ions over the cation sites.
Abstract: Infra-red spectroscopy of carbon dioxide adsorbed on Na-Ca(Mg)-Y faujasites is used to determine the distribution of Ca and Mg ions over the cation sites. Physisorption of CO2 provides a sensitive method for the detection of Ca2+ and Mg2+ in supercage positions. High temperature outgassing of the samples facilitates the migration of bivalent ions from positions in the supercage to the small cavities. Bivalent ions in the dehydrated Y samples are only present in the supercages when the degree of ion exchange is 46 to 48% or higher. For high temperature chemisorption of CO2, the chemisorbed species are closely related to co-ordinated carbonate ions. The concentration of this species does not exceed 2 molecules per unit cell.
TL;DR: In this paper, the reversible component in Pt surface oxidation (demonstrated in Part 1) has been characterised by means of electric modulated reflectance measurements and related to the electrochemical oxide formation and reduction processes studied by mean of cyclic voltammetry.
Abstract: The reversible component in Pt surface oxidation (demonstrated in Part 1) has been characterised by means of electric modulated reflectance measurements and related to the electrochemical oxide formation and reduction processes studied by means of cyclic voltammetry. The reversible component gives a maximum response both in modulated reflectance and a.c. measurements at ca. 0.90 V and then decreases with increasing potential.The reversible component produced in the initial stages of oxidation is consumed at higher potentials or on holding the potential above 0.9 V. This is consistent with potentiodynamic results which show that a more stable oxide is produced at higher potentials or on holding the potential constant for some time and can be reduced only at relatively lower positive potentials. The change of properties of the surface oxide with time and/or with increasing positive potential and coverage, is consistent with a rearrangement of the initially formed ad-layer by a place-exchange mechanism. Such a process is absent at iridium.
TL;DR: In this article, the Arrhenius parameters for the co-pyrolysis of disilane with monosilane or with hydrogen have been calculated from the rate data and thermochemical information.
Abstract: Co-pyrolyses of disilane with monosilane or with hydrogen have been conducted over wide ranges to temperature, pressure and mixture composition. The following Arrhenius parameters for the silene insertion reactions have been calculated from the rate data and thermochemical information: SiH2+ SiH4→ Si2 H6(– 1), SiH2+ Si2H6→ Si3 H8(2), SiH2+ H2→ SiH4(5), log(A–1/l. mol–1 s–1)= 9.7, E–1= 5400 J mol–1; log(A2/l. mol–1 s–1)= 9.85, E2= 1615 J mol–1; log(A5/l. mol–1 s–1)= 9.1; E5= 23 000 J mol–1.Disilane is shown to be a suitable source of silene and the data presented for k2 and E2 now permit extension of the co-pyrolysis method to the evaluation of the rate parameters of a range of other silene insertion reactions.
TL;DR: In this article, the macroscopic theory of van der Waals dispersion forces is used to derive equations for the work of adhesion and contact angle of a liquid on a solid in the presence of a thin layer between them.
Abstract: The macroscopic theory of van der Waals dispersion forces is used to derive equations for the work of adhesion and contact angle of a liquid on a solid in the presence of a thin layer between them. Approximate expressions are also derived in terms of Hamaker constants and surface energies. The results obtained are expected to hold whenever dispersion forces alone are operating between the media.The surface tensions of a number of saturated hydrocarbons are calculated on the basis of macroscopic theory and the results are found to agree well with measured values.
TL;DR: In this paper, carbon dioxide in X-type zeolites exchanged with alkali and alkaline earth metal cations reveals bands in the infra-red spectra due to CO2 in a "bent" configuration.
Abstract: Adsorption of carbon dioxide in X-type zeolites exchanged with alkali and alkaline earth metal cations reveals bands in the infra-red spectra due to CO2 in a “bent” configuration. The spectra are interpreted in terms of carboxylate and carbonate species. Lattice oxygens of the type O1 seem to be involved. The small number of these species fails to correlate with any structural site. When the amount Ca2+ ions in the samples is high enough to occupy sites in both the small and the supercages, new structural species are formed.
TL;DR: In this article, the rate constants of triplet quenching are derived and the pathways of deactivation for triplet acetone in solution are discussed, as well as the quantum yields of acetone disappearance.
Abstract: Kinetic studies of the absorption and emission of triplet acetone and the absorption of the ketyl radical, following flash excitation of acetone in a variety of solvents, are reported as well as the quantum yields of acetone disappearance.Rate constants of triplet quenching are derived and the pathways of deactivation of triplet acetone in solution are discussed.
TL;DR: In this article, the dipolar molecules move co-operatively with their environment in the supercooled liquid state, and the derived dipole moment autocorrelation function has a natural non-exponential dependence upon time.
Abstract: The low frequency dielectric relaxation (1 to 105 Hz) of dipolar systems has been studied in the supercooled liquid state. Studies were made on fluorenone/o-terphenyl, fluorenone/o-terphenyl/triphenylbenzene, fluorenone/o-terphenyl/decalin, and di-n-butyl phthalate/o-terphenyl systems, where the latter system was studied from dilute solution to pure di-n-butyl phthalate. The results show that the dipolar molecules move co-operatively with their environment in the supercooled liquid state, and the derived dipole moment autocorrelation function has a natural non-exponential dependence upon time. It was shown that the fluorenone reorientation rate in o-terphenyl could be made faster by addition of small amounts of decalin, and could be made slower by an addition of small amounts of triphenylbenzene. The concentration dependence of the shape of the relaxation of di-n-butyl phthalate is quite different from that of fluorenone in o-terphenyl, and is analyzed to yield the effective distribution of local concentration surrounding a dipolar molecule. The relationship between dielectric relaxation and other techniques which detect molecular motion is briefly discussed, and the dipole correlation function for dilute supercooled o-terphenyl solutions is used to predict [〈3 cos2θ(t)〉—1]/2 for these systems.
TL;DR: In this article, the authors compare very slow deposition (SSO, slow spray-on) or by deposition in pulses (PMI, pulsed matrix isolation, first introduced by Rochkind).
Abstract: Preparation from the gas phase of matrix-isolated samples at low temperature can be achieved by very slow deposition (SSO, slow spray-on) or by deposition in pulses (PMI, pulsed matrix isolation, first introduced by Rochkind). Infra-red experiments which compare SSO and PMI are described for a variety of systems. These show that (a)“fractional distillation” is similar for both methods, (b) PMI generally produces significantly less polymer than SSO, (c) Beer's law is obeyed for PMI even after many pulses, (d) the spray-on geometry for PMI is not critical and (e) contamination due to apparatus leaks is significantly lower for PMI than SSO. These results combined with the great time economy of PMI and the generally clearer matrices obtained suggest that PMI should be used in preference to SSO where practicable.
TL;DR: In this paper, the C2 to C4 alkenes were isolated in argon matrices at 20 K. The relative intensities in the matrix were in agreement with the small energy difference reported from microwave spectroscopy.
Abstract: Infra-red spectra are reported of the C2 to C4 alkenes isolated in argon matrices at 20 K. Absorptions due to both conformers of but-1-ene were observed, and a complete assignment is given. The relative intensities in the matrix are in agreement with the small energy difference reported from microwave spectroscopy. An assignment of the fundamental modes is presented for each alkene.