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Showing papers in "Canadian Journal of Physics in 1973"


Journal ArticleDOI
TL;DR: In this paper, the method of Kirzhnits for the calculation of quantum corrections to the Thomas-Fermi approximation is reviewed and an equation whose iteration gives quantum corrections is derived.
Abstract: The method of Kirzhnits for the calculation of quantum corrections to the Thomas–Fermi approximation is reviewed. An equation is derived whose iteration gives quantum corrections to the density mat...

239 citations


Journal ArticleDOI
TL;DR: In this paper, the visible fluorescence of the SiF radical in SiF4 gas irradiated by the pulsed output of a CO2 laser leads to the conclusion that the molecules are dissociated into electronically excited fragments by the action of the intense laser field.
Abstract: Observation of the visible fluorescence of the SiF radical in SiF4 gas irradiated by the pulsed output of a CO2 laser leads to the conclusion that the molecules are dissociated into electronically excited fragments by the action of the intense laser field. A clear distinction is observed between the fluorescence produced through this process and that associated with thermalization of the incident energy.

174 citations


Journal ArticleDOI
TL;DR: In this article, the electronic emission and absorption spectrum of HF has been photographed at high resolution with a 10m grating spectrograph and the dissociation energy has been found to be D0(HF)
Abstract: The electronic emission and absorption spectrum of HF has been photographed at high resolution with a 10 m grating spectrograph. The emission, which extends from 2670 to 1480 A, consists entirely of bands of the B1Σ+–X1Σ+ (previously denoted as the V1Σ+–X1Σ+)system. From the analysis of 51 bands of the emission spectrum, constants of the vibrational levels of the X state from ν = 7 and 19 and of the B state from ν = 0 to 10 have been determined. The dissociation energy of HF has been found to be D0(HF) = 47 333 ± 60 cm−1. In the absorption spectrum, 56 bands of the B–X system have been identified. Vibrational levels of the B state between ν = 14 and 26 were found to be well behaved and readily analyzed, but levels between ν = 26 and 73 were found to be highly perturbed. Rydberg–Klein–Rees potential curves have been calculated for the B and X states and it is shown that at large internuclear distances the bonding of the B state is almost entirely ionic.

141 citations


Journal ArticleDOI
TL;DR: In this paper, the strongest features of the gas-phase absorption spectrum of CS2 in the region 2900-3300 A (Kleman's V system) are shown to belong to a 1B2-1Σg+ transition, where the 1B 2 state correlates with the upper Renner-Teller component of the π →π* 1Δu state of the linear molecule.
Abstract: The strongest features of the gas-phase absorption spectrum of CS2 in the region 2900–3300 A (Kleman's V system) are shown to belong to a 1B2–1Σg+ transition, where the 1B2 state correlates with the upper Renner–Teller component of the π → π* 1Δu state of the linear molecule. The barrier to linearity is about 1300 cm−1, and the structure of the molecule in the zero-point level is r(C–S) = 1.544 ± 0.006 A, . Transitions to the lower Renner–Teller component, 1A2(1Δu), have been identified in the region 3340–3500 A: these consist of a progression of vibronic Δ–Δ bands and a weaker progression of Π–Π bands. This is a new type of electronic transition, which does not appear in cold absorption, but whose 'hot' bands derive an amount of intensity proportional to K2 through Renner–Teller mixing (in this case from the V system). The bands of both systems are very severely perturbed: possible causes of the perturbations are discussed.

119 citations


Journal ArticleDOI
TL;DR: In this article, a krypton ion laser operating at 6470°A excites strong resonance fluorescence in nitrogen dioxide gas, and the fluorescence bands have a parallel structure (ΔK = 0) and are assigned to the electronical...
Abstract: A krypton ion laser operating at 6470 A excites strong resonance fluorescence in nitrogen dioxide gas. The fluorescence bands have "parallel" structure (ΔK = 0) and are assigned to the electronical...

69 citations


Journal ArticleDOI
TL;DR: In this paper, a single crystal of rubidium was measured using inelastic neutron scattering and the results, at 12, 85, 120, and 205 °K, were analyzed within the harmonic framework to yield atomic force constants, which were used to compute the phonon frequency distribution and frequency contours in the (100) and planes.
Abstract: Dispersion curves for lattice vibrations propagating along the five major symmetry directions in a single crystal of rubidium have been measured using inelastic neutron scattering. Care has been taken to identify spurious peaks in the neutron groups and to correct for effects of instrumental resolution. The results, at 12, 85, 120, and 205 °K, have been analyzed within the harmonic framework to yield atomic force constants, which were used to compute the phonon frequency distribution and frequency contours in the (100) and planes. A reciprocal space analysis has also been performed. The results are compared with previous measurements on the lighter alkali metals, and with the calculations of Toya and of Price, Singwi, and Tosi.

67 citations


Journal ArticleDOI
TL;DR: In this article, the rotational and vibrational levels of the ground state of D2 have been evaluated up to the last vibrational level, which lies only 2'cm−1 below the dissociation limit, and the deviations of the observed ΔG(ν'+'1/2) and Bv values from theoretical values given by Kolos and Wolniewicz on the basis of ab initio calculations are very small but systematic and are probably due to the neglect of nonadiabatic corrections in theoretical calculations.
Abstract: The Lyman and Werner bands of D2 have been measured under high resolution and their analysis has been extended. From this analysis the rotational and vibrational levels of the ground state of D2 have been evaluated up to the last vibrational level ν = 21 which lies only 2 cm−1 below the dissociation limit. The deviations of the observed ΔG(ν + 1/2) and Bv values from theoretical values given by Kolos and Wolniewicz on the basis of ab initio calculations are very small but systematic and are probably due to the neglect of nonadiabatic corrections in the theoretical calculations. Similar comparisons have been made for the lower vibrational levels of the B1Σu+ and C1Πu− states. Here the differences between theory and experiment are somewhat larger. The observed electronic excitation energies agree with the theoretical ones within 15 cm−1 for 1Σu+ and 8 cm−1 for 1Πu−.

64 citations


Journal ArticleDOI
TL;DR: In this article, the graviton is assumed to have a mass and it is allowed to decay into two photons, from the transition probability for this decay an illustrative restriction is placed upon the mass.
Abstract: The graviton is assumed to have a mass and it is allowed to decay into two photons. From the transition probability for this decay an illustrative restriction is placed upon the graviton mass. Restrictions are also made on the mass with regards to the speed of propagation of gravitational radiation and to the range of gravitational forces.

59 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that a field expansion in terms of E and H modes for an arbitrary current source in a wave guide is complete for points outside the source region but does not give the complete field within the source regions in general.
Abstract: It is shown that a field expansion in terms of E and H modes for an arbitrary current source in a wave guide is complete for points outside the source region but does not give the complete field within the source region in general. It is also shown how the expansion may be completed by the addition of an extra term of simple form.

57 citations


Journal ArticleDOI
TL;DR: In this paper, the authors show that the 2100-A line of Zn+ excites strong resonance fluorescence in sulfur dioxide gas, and that the fluorescence bands form progressions of about 5 members in ν 1, ν 2 and ν 3, singly and in combination.
Abstract: The 2100 A line of Zn+ excites strong resonance fluorescence in sulfur dioxide gas. Vibrational analysis shows that the fluorescence bands form progressions of about 5 members in ν1, ν2, and ν3, singly and in combination. Although the occurrence of transitions to odd- and even-numbered levels of ν3 without discernable alternation in intensity is unexplained, the widespread activity of ν3 provides strong physical evidence for an unsymmetrical (Cs) structure in the upper state of the transition. Rotational analysis indicates that the transition moment is parallel, or nearly parallel, to the a axis and therefore that the upper electronic state of these transitions has B2(A′) orbital symmetry.

55 citations


Journal ArticleDOI
TL;DR: In this article, the absorption spectrum of acrolein-d1 (CH2=CH∙CDO) has been studied in the region 3900 to 4400 A with path lengths and pressures up to 10m atm and temperatures from 25 to 160 °C.
Abstract: The absorption spectrum of acrolein-d1 (CH2=CH∙CDO) has been studied in the region 3900 to 4400 A with path lengths and pressures up to 10 m atm and temperatures from 25 to 160 °C. This study provides additional information for the interpretation of the vibrational structure observed in the 3A″–1A′ (trans), 1A″–1A′ (cis), and 3A″–1A′ (cis) systems of acrolein, in addition to new information for acrolein-d1. Most of the features in these spectra are now assigned.

Journal ArticleDOI
TL;DR: In this paper, one-dimensional dilute systems with nearest neighbor interactions were studied in terms of the power series of the concentration of magnetic atoms, and the specific heats, the susceptibilities and the magnetizations of the ferro magnets and antiferromagnets were obtained.
Abstract: One-dimensional dilute systems with nearest neighbor interactions are studied in terms of power series of the concentration of magnetic atoms. Recurrence relations between coefficients of the power series of the Ising systems are obtained. The Ising systems of S = 1/2 are studied. The specific heats, the susceptibilities, and the magnetizations of the ferro magnets and antiferromagnets are obtained. At low temperatures, three steps in the magnetization of antiferromagnetic systems are found. An Ising system of S = 1/2 with nearest and second nearest neighbor interactions is also studied by extending the method, and the specific heats are obtained when the magnetic field is zero.

Journal ArticleDOI
TL;DR: In this paper, a superconducting thin film tunnel junction (Sn-SnO2-Sn) of total thickness 400nm, area 7'×'10−4'cm2, and normal (4.2 K) resistance 77'm? was prepared on a glass substrate.
Abstract: A superconducting thin film tunnel junction (Sn–SnO2–Sn) of total thickness 400 nm, area 7 × 10−4 cm2, and normal (4.2 K) resistance 77 m? was prepared on a glass substrate. When cooled to 1.2 K and suitably electrically and magnetically biased, the junction was bombarded with 5.1 MeV alpha particles. The resulting pulses induced in the tunnel current were observed to have amplitudes up to 19 times the r.m.s. output noise level. The possibility of utilizing this effect in charged particle spectrometry is explored.

Journal ArticleDOI
TL;DR: In this paper, a reanalysis of the spectroscopic data for I2(B3ΠOu+) was performed to obtain a more complete and internally consistent set of molecular constants and an RKR potential curve.
Abstract: Some new techniques are introduced in a reanalysis of the spectroscopic data for I2(B3ΠOu+)to obtain a more complete and internally consistent set of molecular constants, and an RKR potential curve. In particular, attention is focussed on the determination of reliable high-order rotational constants (Dν, Hν, etc.) for highly excited vibrational levels. The ensuing intermolecular potential for this state is then used together with a known ground-state curve in a study of the J dependence of Franck-Condon factors for discrete B(3ΠOu+)–X(1Σg+) transitions over a wide range of ν and J. It is concluded that at the temperatures 1000–2000 °K routinely achieved in shock-tube experiments, the intensity of most vibrational bands will vary drastically as J ranges across the half-width of the thermal rotational population distribution.

Journal ArticleDOI
TL;DR: In this article, the thermal conductivity, electrical resistivity, and thermoelectric power of polycrystalline specimens of pure Co have been determined in the temperature range of 90 to 1250
Abstract: The thermal conductivity, electrical resistivity, and thermoelectric power of well-characterized, polycrystalline specimens of pure Co have been determined in the temperature range of 90 to 1250 K. Additionally, the measurements of the electrical resistivity have been extended to 1750 K, and the coefficient of thermal expansion measured between 300 and 770 K. The new results are compared with those previously published, and, for the low temperature h.c.p. phase, compared with predictions based on published band structure calculations. Qualitatively, the observed results agree with the predictions, particularly as far as the very unusual temperature variation of the Lorenz function is concerned; quantitative comparisons, however, are impossible, due to the lack of precision in the calculated band structures. The theoretical analysis of the results for the high temperature f.c.c. phase will be given together with that of Ni in Part II.

Journal ArticleDOI
TL;DR: In this article, the total cross sections for elastic scattering of positrons in the energy range from 4 to 19eV have been measured by the method of transmission, and the experimental results agree with those of Costello et al., and marginally with our own 1972 results, but are significantly different from those of Canter et al.
Abstract: The total cross sections for elastic scattering of positrons in the energy range from 4 to 19 eV have been measured by the method of transmission. By varying a magnetic field applied along the axis of the scattering chamber the transmitted fraction of the beam is altered, from which individual phase shifts can be extracted. s-, p-, and d-wave phase shifts are given over the entire energy range. The s-wave phase shifts are in agreement with values published by Drachman in 1968, while the p- and d-wave phase shifts are intermediate between values calculated by the same author in 1966 and 1971. The experimental results agree with those of Costello et al., and marginally with our own 1972 results, but are significantly different from those of Canter et al. We compute that the Ramsauer minimum in the diffusion cross section must be 0.04πa02 at 1.6 eV while the minimum in the total cross section is 0.11πa02 at 2.1 eV. The shoulder breadth observed in annihilation experiments is in nice agreement with what one w...

Journal ArticleDOI
TL;DR: In this paper, the 1Au-1Ag and 3Au−1Ag systems of the trans molecule and the 1B1−1A1 (π*n) system of the cis molecule were assigned to three band systems, viz.
Abstract: Emission spectra of glyoxal, glyoxal-d1, and glyoxal-d2 have been excited using the various lines of an argon ion laser. The bands have been assigned to 3 band systems, viz. the 1Au–1Ag and 3Au–1Ag (π*–n) systems of the trans molecule and the 1B1–1A1 (π*–n) system of the cis molecule. The vibrational constants are in good agreement with earlier values. Some new vibrational constants have been determined.

Journal ArticleDOI
TL;DR: In this paper, a discussion of how to carry out a direct perturbation expansion for the one-electron Green's function is given using an electron-plasmon model for the conduction electron correlations.
Abstract: A discussion of how to carry out a direct perturbation expansion for the one-electron Green's function is given using an electron–plasmon model for the conduction electron correlations. A crucial feature of the method is the consistent extraction of energy shifts. Numerical results for the spectral function and the density of states are given in lowest order and the generalization to higher order is discussed. The present work differs from previous ones in that the method used cannot give rise to "plasmaron"-like excitations. Other singular features also come in differently.

Journal ArticleDOI
TL;DR: In this paper, a mathematical treatment is analyzed, which improves the detection of structures located over a strong continuum and may be used as an adjustable filter, selecting structures according to their natural width.
Abstract: A recently reported mathematical treatment is analyzed, which improves the detection of structures located over a strong continuum. This method does not have the drawbacks of the commonly used differentiation and may be used as an adjustable filter, selecting structures according to their natural width. Detection of autoionizing states in argon and measurement of the energy shift between the ionization thresholds of H/sub 2/ and D/sub 2/ are presented, as examples of application. (auth)

Journal ArticleDOI
TL;DR: In this article, observations of the Q(J) lines in the Raman spectrum of HD are reported for a range of densities at room temperature, and the broadening of individual components at low densities and the eventual overlap and collapse of the band at high densities are shown to be in agreement with the theory of motional narrowing of Alekseev and Sobel aman.
Abstract: Observations of the Q(J) lines in the Raman spectrum of HD are reported for a range of densities at room temperature. The broadening of the individual components at low densities and the eventual overlap and collapse of the band at high densities is shown to be in agreement with the theory of motional narrowing of Alekseev and Sobel'man. A brief comparison of the broadening and shifting of the Q branch of HD with that for H2 is made.

Journal ArticleDOI
TL;DR: In this article, polarization-free measurements of the electron impact excitation of the resonance lines of argon in the energy range 10−2000eV Cross sections are made absolute b.
Abstract: 'Polarization-free' measurements are presented of the electron impact excitation of the 1048 A and 1067 A resonance lines of argon in the energy range 10–2000 eV Cross sections are made absolute b

Journal ArticleDOI
TL;DR: In this paper, a configuration-interaction calculation of the electronic energies of the OH radical has been performed, using from 34 to 46 configurations for doublet states; and from 11 to 25 configurations for the quartet states.
Abstract: A configuration-interaction calculation of the electronic energies of the OH radical has been performed, using from 34 to 46 configurations for the doublet states; and from 11 to 25 configurations for the quartet states. The results are presented for the six lowest states of 2Σ+, 2Σ−, 2Π, 2Δ; 4Σ+, 4Σ−, 4Π, and 4Δ symmetries. The calculations have been performed for a range of internuclear distances from 0.8 to 3 A. The method of computation has been designed to give the kind of accuracy for the lowest three or four states of each symmetry which could be useful in the empirical analysis of the hitherto unanalyzed spectrum of OH in the 1850 A region.

Journal ArticleDOI
TL;DR: In this paper, the beamfoil technique was used to study the Neon spectra between 379 and 914 A. Mean lives have been obtained for 21 levels in Ne I − Ne VII.
Abstract: Neon spectra between 379 and 914 A were studied by the beam-foil technique. Mean lives have been obtained for 21 levels in Ne I – Ne VII. In addition, mean lives are reported for upper levels of 12 unassigned lines.

Journal ArticleDOI
TL;DR: In this paper, rotational analysis of over 50 sub-bands of three emission transitions of 74GeF has given vibrational and rotational constants for the four lowest-lying electronic states of GeF.
Abstract: Rotational analysis of over 50 sub-bands of three emission transitions of 74GeF has given vibrational and rotational constants for the four lowest-lying electronic states of GeF. One of these is a 4Σ− state in Hund's case (a), where all four spin components have been identified. Extensive perturbations between this 4Σ− state and the B2Σ+ state have been analyzed in detail: the two states appear to interact mainly by a second-order mechanism through the so far uncharacterized σπ22Σ+ state, but the surprisingly large J dependence of the perturbation matrix element suggests that another mechanism, possibly involving the ground state, may contribute. Further perturbations, where the lines show an unusual intensity enhancement, appear in those sub-bands with B2Σ+ ν = 4 as upper state.

Journal ArticleDOI
TL;DR: In this article, the authors measured radiative lifetimes for 19 excited levels in F I-IV and Si II-IV by the beam-foil technique and compared with theory and experiment where possible.
Abstract: We have measured radiative lifetimes for 19 excited levels in F I–IV and Si II–IV by the beam–foil technique. The production of silicon beams by the use of SF6 as the source gas is discussed. The lifetime results are compared with theory and experiment where possible, and 7 new experimental lifetimes are presented.

Journal ArticleDOI
TL;DR: In this article, angular distributions for the (d,t) angular distributions and the ratios of (3He,α) and (d-t) cross sections were derived for the 152Sm(d, t) 151Sm reaction and spectra at several angles.
Abstract: Properties of nuclear levels in 151Sm have been studied by measuring angular distributions for the 152Sm(d,t)151Sm reaction and spectra at several angles for the 152Sm(3He,α)151Sm and 150Sm(d,p)151Sm reactions. The reaction products were analyzed with a magnetic spectrograph and detected with photographic emulsions. Transfer l values were deduced from the (d,t) angular distributions and from the ratios of (3He,α) and (d,t) cross sections. The (d,t), (d,p), and (3He,α) reactions on targets of 151Sm were also studied in order to learn more about the wave function of the 151Sm ground state. The low-lying positive parity levels can be described by the Nilsson model with Coriolis and ΔN = 2 interactions included. However, the properties of the low energy negative parity states could not be explained as easily. No mixture of Nilsson states was found which could simultaneously explain the single neutron transfer intensities and the Coulomb excitation probabilities from previous measurements.

Journal ArticleDOI
TL;DR: The CO fluorescence of the a′ 3Σ+, d3Δi, and e3Σ−∆→a3Π systems, produced by photodissociation of CO2, was identified and analyzed in this article.
Abstract: The CO fluorescence of the a′ 3Σ+, d3Δi, and e3Σ− → a3Π systems, produced by photodissociation of CO2 is identified and analyzed and the population distributions of the vibrational levels of the a′...

Journal ArticleDOI
TL;DR: In this article, the second-order Raman spectrum of GaP has been investigated experimentally and critical point analysis of the data has been carried out with the aid of the polarization selection rules.
Abstract: The second-order Raman spectrum of GaP has been investigated experimentally. The experiments were performed on oriented single crystals at both 300 and 77 °K. A critical point analysis of the data has been carried out with the aid of the polarization selection rules. The resulting frequencies are also consistent with a theoretical model which in turn is used to calculate the phonon dispersion throughout the Brillouin zone. The one- and two-phonon density of states and the specific heat have also been calculated and compared to our spectra and available specific heat data. The calculated quantities have also been compared to similar quantities obtained from neutron scattering experiments. This comparison provides information on the accuracy and reliability of phonon dispersion curves obtained from Raman scattering experiments.

Journal ArticleDOI
TL;DR: In this article, a Langmuir probe technique has been used to measure electron energy distribution functions in the positive column of a DC glow discharge in oxygen, where the average electron energies lie between 4.4 and 5.0
Abstract: A Langmuir probe technique has been used to measure electron energy distribution functions in the positive column of a DC glow discharge in oxygen. The electron energy distribution function is shown to fit a functional form given by f(E) = CE1/2 exp (−BEn) where n = 1.6 ± 0.1; the average electron energies lie between 4.4 and 5.0 eV.

Journal ArticleDOI
TL;DR: In this paper, the Triton spectra from the 154Gd(d,t)153Gd reaction have been measured at 15 angles using a beam of 15'MeV deuterons.
Abstract: Triton spectra from the 154Gd(d,t)153Gd reaction have been measured at 15 angles using a beam of 15 MeV deuterons. The 154Gd(3He,α)153Gd reaction was studied at 4 angles with a 24 MeV 3He beam. The reaction products were analyzed with an Enge-type magnetic spectrograph and detected with photographic emulsions. The (d,t) angular distributions and ratios of the (3He,α) and (d,t) cross sections were used to determine l values for a number of transitions. Members of the strongly perturbed band consisting of a mixture of Nilsson states from the i13/2 shell have been populated. An attempt has been made to describe some of the positive parity states in terms of the Nilsson model with Coriolis and ΔN = 2 mixings included. As spin assignments are now available for a large number of positive parity levels, it is possible to see a better developed pattern for this mixing than was presented previously. Although the observed intensity pattern for the 3/2−[521] ground-state band agrees with expectations, the remaining ...