Showing papers on "Photoexcitation published in 1997"
19 Sep 1997
Abstract: The Evaluated Photon Data Library, 1997 version (EPLD97), is designed for use in photon transport calculations at Lawrence Livermore National Laboratory This library includes photon interaction data for all elements with atomic number between Z = 1 (hydrogne) and 100 (fermium), including: photoionization, photoexcitation, coherent and incoherent scattering, and pair and triplet porduction cross sections For use in applications data is provided for all elements over the energy range 1 eV to 100 GeV This report documents the sources and treatment of the data included inthis library EPDL97 completely supersedes the earlier 1989 version of EPDL and it is highly recommended that useres only use the most recent version of this library
515 citations
TL;DR: In this paper, the authors show that spontaneous fluctuations in the spectra of immobilized single dye molecules occur on two different timescales: hundreds of milliseconds and tens of seconds, indicating that these fluctuations have two distinct activation energies.
Abstract: RECENT advances in near-field1and far-field2,3 fluorescence microscopy have made it possible to image single molecules and measure their emission3,4 and excitation5 spectra and fluorescence lifetimes3,6–8 at room temperature. These studies have revealed spectral shifts4 and intensity fluctuations6,7, the origins of which are not clear. Here we show that spontaneous fluctuations in the spectra of immobilized single dye molecules occur on two different timescales: hundreds of milliseconds and tens of seconds, indicating that these fluctuations have two distinct activation energies. In addition, we see photoinduced spectral fluctuations on repeated photoexcitation of single molecules. We suggest that all of these fluctuations can be understood as transitions between metastable minima in the molecular potential-energy surface.
316 citations
TL;DR: In this paper, the electronic dynamics of gold nanocrystals, passivated by a monolayer of alkylthiol(ate) groups, were studied by transient spectroscopy after excitation with subpicosecond laser pulses.
Abstract: The electronic dynamics of gold nanocrystals, passivated by a monolayer of alkylthiol(ate) groups, were studied by transient spectroscopy after excitation with subpicosecond laser pulses. Three solution-phase gold samples with average particle size of 1.9, 2.6, and 3.2 nm with size distribution less than 10% were used. The photoexcitation in the intraband (surface plasmon region) leads to the heating of the conduction electron gas and its subsequent thermalization through electron−electron and electron−phonon interaction. The results are analyzed in terms of the contribution of the equilibrated “hot” electrons to the surface plasmon resonance of gold. A different spectral response was observed for different sizes of gold nanoparticles. The results were compared to the dynamics of the large (30 nm diameter) gold nanocrystals colloidal solution. The size-dependent spectral changes are attributed to the reduction of the density of states for small nanoparticles. The observed variation in the kinetics of the ...
306 citations
TL;DR: In this article, the Coulomb interaction parameters for poly(para-phenylenevinylene) have been investigated in a model Hamiltonian with variable on-site and long-range Coulomb interactions between the electrons.
Abstract: Within a model Hamiltonian with variable on-site and long-range Coulomb interactions between the \ensuremath{\pi} electrons for poly(para-phenylenevinylene), we conduct a thorough search in the parameter space to determine the magnitudes of the effective Coulomb interaction parameters necessary to fit all four absorption bands that are seen in the experimental absorption spectra of this material. We find best agreement between the calculated and experimental absorption spectra with Coulomb interactions that are slightly smaller than the standard Pariser-Parr-Pople parameters. For these values of the Coulomb parameters, the primary photoexcitation in poly(para-phenylenevinylene) is to an exciton with binding energy close to 0.9\ifmmode\pm\else\textpm\fi{}0.2 eV. This result, obtained from fitting the linear absorption, is in agreement with nonlinear absorption studies, viz. electroabsorption, two-photon absorption, and picosecond photoinduced absorption, within our model. We have also calculated the energies of the lowest triplet state, and the final state to which triplet absorption occurs. The excited triplet state is an exciton. We show that the latter result, taken together with the known experimental triplet absorption energy, indicates that estimates of 0.2 eV or less for the binding energy are incorrect. We briefly discuss the possibility that the binding energy has an intermediate magnitude.
119 citations
TL;DR: In this article, the authors attributed the observed increase in the 2DEG carrier density and mobility to the photoionization of deep level impurities (DX like centers) in the AlGaN barrier material.
Abstract: Persistent photoconductivity (PPC) effect associated with a two-dimensional electron gas (2DEG) in an AlGaN/GaN heterojunction device has been observed. As a consequence, the device was observed to be sensitive to light and the sensitivity was associated with a permanent photoinduced increase in the 2DEG carrier mobility and density. By formulating the PPC buildup and decay kinetics, we attributed the observed increase in the 2DEG carrier density and mobility to the photoionization of deep level impurities (DX like centers) in the AlGaN barrier material. In the PPC state, we were able to continuously vary the 2DEG carrier density in a single sample through photoexcitation and it has been found that the 2DEG carrier mobility increases almost linearly with the carrier density in the 2DEG channel. At 10 K, an electron mobility of 5800 cm2/V⋅s has been obtained in a PPC state. Implications of these observations on the device applications based on AlGaN/GaN heterojunctions have also been discussed.
119 citations
TL;DR: In this paper, a collisional reduction of the corresponding cations and studied by the variable variable function was proposed to generate hydroxysulfinyl radical (1), hydrogensulfonyl radical (2), and dihydroxynysulfane (6) in the gas phase.
Abstract: Hydroxysulfinyl radical (1), hydrogensulfonyl radical (2), and dihydroxysulfane (6) were generated in the gas phase by collisional reduction of the corresponding cations and studied by the variable...
114 citations
TL;DR: Analysis of the data for all six compounds studied indicates that the shape of the adiabatic surface on which electron transfer occurs can be obtained from the charge transfer band accurately enough to successfully predict the electron transfer rate constant and that explicit tunneling corrections are not required for these compounds.
Abstract: The radical cations of properly designed bishydrazines allow comparison of observed and calculated electron transfer rate constants. These compounds have rate constants small enough to be measured by dynamic electron spin resonance spectroscopy and show charge transfer bands corresponding to vertical excitation from the energy well for the charge occurring upon one hydrazine unit to that for the electron-transferred species. Analysis of the data for all six compounds studied indicates that the shape of the adiabatic surface on which electron transfer occurs can be obtained from the charge transfer band accurately enough to successfully predict the electron transfer rate constant and that explicit tunneling corrections are not required for these compounds.
109 citations
TL;DR: In this article, a semi-empirical diatomics-in-molecules (DIM) excited state electronic structure technique is used to compute the ion pair states of the I2-rare gas crystal system and use these states together with a model of the configurational dependence of the electronic dipole operator matrix elements to calculate the time resolved probe absorption signals in these pump-probe experiments using a simple golden rule result.
Abstract: Recent experimental studies of both A and B state photoexcitation of I2 and the ensuing many-body dynamics in rare gas matrices by Apkarian and co-workers are simulated using the methods we presented in an earlier work combining nonadiabatic molecular dynamics with semiempirical diatomics-in-molecules (DIM) excited state electronic structure techniques. We extend our DIM methods to compute the ion pair states of the I2-rare gas crystal system and use these states together with a model of the configurational dependence of the electronic dipole operator matrix elements to calculate the time resolved probe absorption signals in these pump - probe experiments using a simple golden rule result. Our computed signals are in remarkable agreement with experiments and we use our calculations to provide a detailed microscopic analysis of the channels to predissociation and recombination underlying these experiments.
106 citations
TL;DR: In this article, the authors studied the photoluminescence of films of poly-p$-phenylenevinylene (PPV) and changes of its intensity under conditions of electron spin resonance as a function of temperature and light intensity.
Abstract: Photoluminescence of films of poly-$(p$-phenylenevinylene) (PPV), and changes of its intensity under conditions of electron spin resonance as a function of temperature and light intensity were studied. The experimental technique was based on the modulation of the spin state of paramagnetic species by resonant microwave transitions between Zeeman sublevels of dynamically spin-polarized pairs. Three types of resonant signals were found in the magnetic resonance spectrum: (i) a narrow (1.7 mT width at the half height), (ii) a broad (140 mT) enhancement signal at $g$=2, and (iii) the signal at $g$=4. The results permitted one to conclude that Coulomb bound polaron pairs are produced in PPV with high yield under 488-nm photoexcitation. The narrow signal is assumed to appear due to microwave-induced resonant transitions in triplet polaron pairs. This implies that the resonant transitions change the rate of geminate recombination of the pairs that leads to the formation of triplet intrachain excitons. Those excitons annihilate in the second-order reaction and show themselves in the intensity of the photoluminescence. The annihilation rate was found to be influenced by resonant transitions in triplet exciton pairs as well and resulted in broad and $g$=4 signals. The lifetime of triplet intrachain excitons was estimated from microwave modulation frequency dependence of resonant signal intensities. The results showed that the energy level of the lowest polaron pair state situated below that of singlet intrachain exciton can act as a sink of the excitation energy influencing the quantum yields of the photoluminescence, electroluminescence, and photoconductivity.
92 citations
TL;DR: In this paper, the relation of the increase and decrease with temperature in the integrated intensity is complementary with each other between the luminescence-band V Cu and the X O -Γ 12 -exciton luminecence over T = 4.2-230 K, and the relative magnitudes of the intensity of the band V O 2+ cross over each other at the vicinity of the energy level of exciton, λ∼610 nm.
Abstract: Variations of optical absorption and especially of photoluminescence spectra of Cu 2 O with photoexcitation wavelength and temperature have been for the first time investigated in details. We have newly observed that the relation of the increase and decrease with temperature in the integrated intensity is complementary with each other between the luminescence-band V Cu and the X O -Γ 12 - exciton luminescence over T =4.2–230 K, and the relative magnitudes of the intensity of the band V Cu and V O 2+ cross over each other at the vicinity of the energy level of exciton, λ∼610 nm. We recognize the evidences of the recombination processes of the excitons coupled with vacancies levels. These phenomena indicate universal natures even among the different quality of specimens. Thus, we request a consideration based on the many-body aspect.
86 citations
TL;DR: In this article, a systematic study of low-temperature-grown GaAs, as-grown and annealed, reveal carrier lifetimes to be directly related to the excess arsenic incorporation and the anneal conditions.
Abstract: Subpicosecond electron lifetimes in low-temperature-grown GaAs are unambiguously demonstrated via far infrared terahertz spectroscopy. A systematic study of low-temperature-grown GaAs, as-grown and annealed, reveal carrier lifetimes to be directly related to the excess arsenic incorporation and anneal conditions. Contrary to previous observations, electron lifetimes of 600 fs (200 fs) are found in 0.25% (0.5%) excess arsenic GaAs. We attribute the observed differences to the far infrared interaction and the use of dilute photoexcitation densities which eliminate both band-edge resonance and high carrier densities effects. A simple model is developed to determine the relative electron mobility and to interpret the results. Additionally, time resolved differential spectroscopy reveals Drude-like behavior of the free carrier conductivity within 1 ps of excitation.
TL;DR: In this article, the absorption spectrum, measured via photoexcitation, shows a monomer-like shape independent of film thickness, indicating an amorphous structure, and the monotonic red-shift with increasing d reflects enhancement of isotropic intermolecular interaction.
TL;DR: A femtosecond transient absorption spectroscopic study on nickel(II) porphyrins in various solvents was carried out in this paper to obtain detailed information on vibrational relaxation processes occurring in the initial stage after photoexcitation to the highly excited states.
Abstract: We have carried out a femtosecond transient absorption spectroscopic study on nickel(II) porphyrins in various solvents in order to obtain detailed information on vibrational relaxation processes occurring in the initial stage after photoexcitation to the highly excited states. We found the decay process of time constant of approximately 1 ps corresponding to the intramolecular vibrational relaxation process for Ni(II)TPP and Ni(II)OEP in toluene. In addition to this process, the intermolecular vibrational relaxation process with 10−20 ps lifetime was also observed for Ni(II)OEP in toluene, although its contribution to the overall decay process is relatively weak probably due to the weak solute/solvent interaction. In coordinating solvents such as pyridine and piperidine, we observed the intramolecular vibrational relaxation processes before complete population of the bottleneck excited metal 1|0,dz2〉 or 3|0,3(d,d)〉 state. In this case, it is likely that the intermolecular vibrational relaxation process a...
TL;DR: In this article, the luminescence of narrow quantum wires at photoexcitation densities of up to similar to 3 x 10(6) cm(-1) was studied and it was shown that excitonic recombination dominates over other recombination channels in stark contrast with the behavior of quantum wells and bulk structures at equivalent densities.
Abstract: We have studied the luminescence of narrow quantum wires at photoexcitation densities of up to similar to 3 x 10(6) cm(-1). We show that even at these densities, which are well above the expected Mott density of 8 x 10(5) cm(-1), excitonic recombination dominates over other recombination channels in stark contrast with the behavior of quantum wells and bulk structures at equivalent densities. As we observe no significant shift in the peak energy with density, an upper limit to the band gap renormalization can be set.
TL;DR: In this paper, the spin-orbit state distribution of the chlorine fragment, [Cl(2P1/2)]/[Cl( 2P3/2] = 0.69±0.02, in excellent agreement with recent theoretical studies.
Abstract: HCl was photodissociated by ultraviolet (uv) radiation at 193.3 nm. Time-of-flight spectra of the hydrogen atom fragment provided the spin–orbit state distribution of the chlorine fragment, [Cl(2P1/2)]/[Cl(2P3/2)]=0.69±0.02, in excellent agreement with recent theoretical studies. The H atom angular distribution studied by changing the uv photolysis laser polarization confirmed a dominant A 1Π←X 1Σ+ electronic transition in the photoexcitation process (β=−1.01±0.04 and β*=−0.94±0.07).
TL;DR: In this article, the authors examined the various photoexcitation pathways involved in populating these molecular states and determined the absorption and excitation spectra and the quantum efficiency of the photoluminescence as a function of the crystallite size.
Abstract: Intrinsic localized radiative surface states belonging to Si-Si dimers on the surface of silicon nanocrystallites have been recently predicted. We examine the various photoexcitation pathways involved in populating these molecular states. We include both direct excitation from the ground state and indirect excitation from the photoexcited delocalized excitonic states via quantum tunneling and thermal activation. We determine the absorption and excitation spectra and the quantum efficiency of the photoluminescence as a function of the crystallite size. Our calculation gives a dramatic enhancement in the efficiency for sizes below a critical size of about 1.4 nm.
TL;DR: In this paper, the authors used pulsed-laser-excitation/resonance fluorescence technique to assess the efficiency of OH formation following photoexcitation of NO2 at discrete wavelengths beyond the photodissociation threshold in the presence of water vapor.
Abstract: The pulsed-laser-excitation/resonance fluorescence technique was used to assess the efficiency of OH formation following photoexcitation of NO2 at discrete wavelengths beyond the photodissociation threshold in the presence of water vapor: NO2* + H2O → HONO + OH. Excitation at wavelengths between 432 and 449 nm was found to lead to OH production via a facile sequential two-photon absorption by NO2, leading to O(1D) and thus to OH in the presence of H2O, i.e., NO2 + hν → NO2*, NO2* + hν → NO2**, NO2** → NO + O(1D), O(1D) + H2O → 2OH. The cross section for the transition NO2** ← NO2* was found to be similar to that for the NO2* ← NO2 transition at 435 nm. At 532 nm, the two-photon process is not sufficiently energetic to form O(1D), and OH is not observed. An upper limit of approximately 7 × 10-5 is found for the reactive quenching of NO2* by water vapor relative to collisional quenching. The atmospheric relevance of OH formation via NO2 excitation is discussed.
TL;DR: In this article, the resonance Raman spectra for trans-azobenzene in carbon tetrachloride using 16 excitation wavelengths in the region from 355-600 nm have been recorded.
Abstract: Resonance Raman spectra have been recorded for trans- azobenzene in carbon tetrachloride using 16 excitation wavelengths in the region from 355–600 nm. It has been observed that for many totally symmetric fundamentals viz. C–N, N5N stretch, etc., the resonance Raman intensities decrease near the maxima of the resonant electronic $(2 ^1A_g \leftarrow1 ^1A_g)$ transition. This is attributed to interference due to preresonant scattering from the strongly allowed $(1 ^1A_u \leftarrow1 ^1A_g)$ electronic transition. The Raman excitation profiles (REPs) for the ten Franck–Condon active fundamentals have been successfully modeled using Heller’s time-dependent approach with the inclusion of interference effect from higher electronic state. The short time isomerization dynamics is then examined from a priori knowledge of ground-state normal mode descriptions to convert the wave packet motion in dimensionless normal coordinates to internal coordinates. It is observed that within 5–30 fs of photoexcitation, the major changes experienced by trans-azobenzene are on N = N and C–N stretching vibrations, while N = N suffers reduction, C–N bond elongates, and with time the ring C atoms distort relatively out of the plane.
TL;DR: In this paper, narrow optical emission bands (fwhm 5-10 nm) are observed on laser photoexcitation of solid films of certain fluorescent polymers composed of phenylene and vinylene or acetylene units.
TL;DR: In this paper, a time resolved core level spectroscopy study was performed on photoexcited Si(111)2×1 surfaces with subnanosecond resolution, which enabled measuring band bending fluctuations, caused by surface carrier dynamics, during the first nanosecond after photoexcitation; differences in the Si2p core level lineshape, dependent on the pumpprobe time delay, were also observed.
Abstract: Combining the use of a UV storage ring free electron laser and of synchrotron radiation, a time resolved core level spectroscopy study has been performed on photoexcited Si(111)2×1 surfaces with subnanosecond resolution. This enabled us to measure band bending fluctuations, caused by surface carrier dynamics, during the first nanosecond after photoexcitation; differences in the Si2p core level lineshape, dependent on the pump-probe time delay, were also observed. The presence of defects was found to reduce the fluctuations and make the carrier recombination process faster.
Patent•
09 Dec 1997TL;DR: In this article, a method for highly hydrophilifying the surface of an article by photoexcitation of a semiconductor photocatalyst and maintaining the hydrophilicicity is disclosed.
Abstract: A method for highly hydrophilifying the surface of an article by photoexcitation of a semiconductor photocatalyst and maintaining the hydrophilicity is disclosed. A layer containing a photocatalyst is formed on a substrate. Onto the surface of the layer are fixed a hydroxyl group upon photoexcitation of the photocatalyst and a physically adsorbed water molecule in the vicinity of the hydroxyl group upon photoexcitation of the photocatalyst. Thus, the surface is highly hydrophilified. Further, this surface, simultaneously with the hydrophilification, exhibits higher hydrophobicity.
TL;DR: In this article, the energy dependence of photoexcited electrons in copper was measured using femtosecond time-resolved photoemission spectroscopy to within 0.3 eV above the Fermi level.
Abstract: The energy dependence of the relaxation of photoexcited electrons in copper was measured using femtosecond time-resolved photoemission spectroscopy to within 0.3 eV above the Fermi level. By performing lifetime measurements under different surface conditions, several surface dynamical processes were investigated. In particular, an anomalous long lifetime feature, which cannot be explained with Fermi-liquid theory, was observed in the lifetime-energy curve. This feature was found originating from the photoexcitation of the strongly localized Cu $3d$ electrons.
TL;DR: In this paper, the Coulomb blockade oscillations around the few-electron regime in an asymmetric Si single-electron transistor were investigated, and a novel type of photocurrent was observed, which can be attributed to the interplay of photogenerated holes and singleelectron tunneling via the island.
Abstract: We observed a novel type of photocurrent by investigating Coulomb blockade oscillations around the few-electron regime in an asymmetric Si single-electron transistor. Photoexcitation generates new current peaks below the threshold voltage only for one polarity of source-drain voltage. Under low excitation, such photocurrent exhibits intermittent behavior with sudden drops and rises. The phenomena can be ascribed to the interplay of photogenerated holes and single-electron tunneling via the island. The sudden drop is a manifestation of single-electron recombination with a hole in the island.
TL;DR: In this article, the photoisomerization kinetics of D2 bisazo dye and the excitation transfer from dye to nematic liquid crystal host were studied using dynamic holography and polarimetric techniques.
Abstract: Dynamic holography and polarimetric techniques are used to study the photoisomerization kinetics of D2 bisazo dye and the excitation transfer from dye to nematic liquid crystal host. As a result of this transfer, transient modulation of the orientational order parameter, three-dimensional long-scale molecular transient rotation and equilibrated two-dimensional molecular rotations are identified in the host. Amplified rotation of nematic molecules is observed which is much more efficient for the dye photoexcitation with a wavelength in the red rather than in the blue side of its absorption band. The possible role of dye photoisomerization mechanism in these processes is discussed. The dynamic character of the dye induced torque and the presence of long-living intermediate states during photoisomerization and their diffusion are suggested.
TL;DR: In this article, the optical properties of quinquethiophene molecules included in a peryhydrotriphenylene matrix are discussed from a critical comparison of experimental and theoretical data and compared to the situation encountered in solutions and crystals.
TL;DR: In this paper, the resonance Raman spectra of cyclohexane were obtained with excitation throughout the 2B1−2A2 electronic transition, demonstrating that excited-state structural evolution along all three coordinates occurs upon photoexcitation.
Abstract: Resonance Raman spectra of chlorine dioxide (OClO) dissolved in cyclohexane obtained with excitation throughout the 2B1−2A2 electronic transition are presented. Resonance Raman intensity corresponding to all vibrational degrees of freedom (the symmetric stretch, bend, and asymmetric stretch) is observed, demonstrating that excited-state structural evolution along all three coordinates occurs upon photoexcitation. The electronic absorption and absolute resonance Raman cross sections are reproduced employing the time-dependent formalism for Raman scattering using an anharmonic description of the 2A2, excited-state potential-energy surface. Analysis of the resonance Raman cross-sections demonstrates that both homogeneous and inhomogeneous broadening mechanisms are operative in cyclohexane. Comparison of the experimentally determined, gas-phase 2A2 surface to that in solution defined by the analysis presented here shows that although displacements along the symmetric stretch and bend are similar in both phase...
TL;DR: In this article, a superposition of the density grating (Dens.G) signal and the temperature grating signal was used to obtain the rise profile of the pure Temp.G signal, which was analyzed in terms of the deactivation from the photoexcited state.
Abstract: Transient grating signals after photoexcitation to electronically excited states of FeCl3 and o-hydroxybenzophenone (o-HBP) in aqueous solutions were investigated at various temperatures with short-pulsed laser systems. The observed signals can be expressed by a superposition of the density grating (Dens.G) signal and the temperature grating (Temp.G) signal. Above 4 °C, an acoustic oscillation is predominant in the signal, while the acoustic oscillation disappears and a pure Temp.G signal is observed clearly at 4 °C. The rise profile of the pure Temp.G signal was analyzed in terms of the deactivation from the photoexcited state, and it is found that a very fast thermalization process takes place among the solvent molecules. The lifetime of the charge-transfer state of [Fe(OH)(H2O)5]2+ is determined to be 55 ps from the rise profile of the Temp.G signal. Using a subpicosecond laser system and the population grating signal, two time constants (400 fs and 7.5 ps) are obtained for the dynamics of o-HBP. The d...
TL;DR: In this paper, the gas-phase photodissociation dynamics of methane after excitation at the Lyman-α wavelength (121.6 nm) was investigated under collision-free conditions at room temperature.
TL;DR: A weak lithium photoexcitation resonance with completely empty K and L shells (KL -hollow lithium) has been discovered using synchrotron radiation and photoion spectroscopy as discussed by the authors.
Abstract: A weak lithium photoexcitation resonance with completely empty K and L shells (KL -hollow lithium) has been discovered using synchrotron radiation and photoion spectroscopy. This Li (3,3,3) resonance was observed in the doubly charged Li{sup ++} photoion yield spectrum at 175.25eV and demonstrates electron correlation involving all three electrons in the excitation process. Resonance parameters obtained from the data show excellent agreement with the multiconfiguration Dirac-Fock calculation which assigns 3s{sup 2}3p as the dominant configuration. {copyright} {ital 1997} {ital The American Physical Society}
TL;DR: In this paper, an electron scavenger was added to the liquid and probing the transient absorption at three different wavelengths (800 nm, 1500 nm, and 2250 nm) made it possible to distinguish the transient absorbing due to excess electrons from that due to other absorbing species.
Abstract: We report on time resolved optical pump-probe investigations of the electron-cation recombination in alkane liquids. The alkanes were excited via two-photon excitation, using intense sub-picosecond pulses at 266 nm. Adding an electron scavenger to the liquid and probing the transient absorption at three different wavelengths (800 nm, 1500 nm, and 2250 nm) made it possible to distinguish the transient absorption due to excess electrons from that due to other absorbing species. The experimentally observed charge-recombination kinetics in n-hexane and n-octane could be fairly well reproduced by computer simulations in which the initial electron thermalization distance distribution was taken to be f(r)r2dr=(1/b)exp(−r/b)dr. Other distributions, such as a Gaussian, gave unsatisfactory results. The average electron thermalization distance in n-hexane was found to be 35±5 A and in n-octane it was found to be 70±10 A. The results for isooctane could be described either by the distribution (1/b)exp(−r/b)dr with an...