Anisotropic magnetic susceptibility and phase transitions in intercalated graphite: KC24

We measured the magnetic susceptibility of KC₂₄ from 4.2 to 300 K and found no anomalies near the phase transitions at 95 and 123 K as observed in the resistivity. We conclude that the transitions must be due to order- disorder transitions of the K atoms and not charge density wave formation. The susceptibility is anisotropic; at room temperature $\text{χ}{}_{\mathrm{g}}\text{(}\text{H}\text{6}\text{c}\text{)= + 1.50 × 10}{}^{-6}\text{emu g}{}^{-1}\text{± 2\%}$ and $\text{χ}{}_{\mathrm{g}}\text{(}\text{H}\text{⊥}\text{c}\text{)= + 0.045 × 10}{}^{-6}\text{emu g}{}^{-1}\text{± 50\%}$. This anisotropy is not understood in terms of simple rigid band extensions of the band structure of graphite.     

Electron paramagnetic resonance of 61Ni+ in CuGaS2

EPR of ⁶¹Ni⁺ doped CuGaS₂ at 4.2 K leads to the following experimental data: $\text{g = 1.918 ± 0.006 A  < 12 × 10}{}^{-4}\text{cm}{}^{-1}\text{, g}{}_{\mathrm{\perp }}\text{= 2.328±0.006 A}{}_{\mathrm{\perp }}\text{= (65±2) × 10}{}^{-4}\text{cm}{}^{-1}$. High axial field splitting of ²T₂ state stabilizes the center against Jahn-Teller interaction. Covalency reduction factor k is 0.76.     

Elastic constants of LaB6 at room temperature

Measurements have been made of the transit times of pulses of longitudinal and transverse ultrasonic waves propagating in single crystal LaB₆ at room temperature. A unique set of values for the three independent elastic constants has been calculated from the resultant velocities and is; C₁₁ = (45.33 ± 0.11) × 10¹¹dynecm^-2, $\text{C}{}_{12}\text{= (1.82 ± 0.17) × 10}{}^{11}\text{dyne}\text{cm}{}^2$ and C₄₄ = (9.01 ± 0.05) × 10¹¹dyne/cm². The Debye temperature of LaB₆ from these measurements is 773 K, which agrees relatively well with the X-ray Debye temperature, however, differs much from the calorimetric and electrical resistance Debye temperatures.     

Strengths and lorentz broadening coefficients for spectral lines in the ν3 and ν2 + ν4 bands of 12CH4 and 13CH4

Line strengths and self- and nitrogen-broadened half-widths were measured for spectral lines in the ν₃ and ν₂ + ν₄ bands of ¹²CH₄ and ¹³CH₄ from 2870–2883 cm^?1 using a tunable diode laser spectrometer. From measurements made over a temperature range from 215 to 297 K, on samples of ¹²CH₄ broadened with N₂, we deduced that the average temperature coefficients n, defined as $\text{b}{}_{\mathrm{<mtext>L</mtext>}}{}^0\text{(T) = b}{}_{\mathrm{<mtext>L</mtext>}}{}^0\text{(T}{}_0\text{)(}\text{T}\text{T}{}_0\text{)}{}^{\mathrm{?n}}$, of the Lorentz broadening coefficients for the ν₃ and ν₂ + ν₄ bands of ¹²CH₄ were 0.97 ± 0.03 and 0.89 ± 0.04, respectively. A smaller increase is observed in line half-width with increasing pressure for E-species lines, for both self- and nitrogen-broadening, than for other symmetry species lines over the range of pressures measured, 70 to 100 Torr.     

Infrared bands of 12C2HD

The rotational structure of about 40 bands of ¹²C₂HD observed in the region 6000?600 cm^?1 has been measured and interpreted with the purpose of determining a comprehensive set of molecular constants for this isotopic variety of acetylene. Combining these data with the results for ¹²C₂H₂ and ¹²C₂D₂, a reevaluation of the equilibrium internuclear distances for the acetylene molecule has been made: $\text{r}{}_{\mathrm{e}}\text{(CH) = 1.06215 ± 17 × 10}{}^{\mathrm{?5}}\text{A}\text{?}$ and $\text{r}{}_{\mathrm{e}}\text{(CC) = 1.20257 ± 9 × 10}{}^{\mathrm{?5}}\text{A}\text{?}$ were obtained. This paper presents all the molecular constants derived in this study.     

Polarization spectroscopy of the E0g+-B0u+ band system of Br2

The E-B (0_g⁺-0_u⁺) band system of Br₂ has been investigated at Doppler-limited resolution using polarization labeling spectroscopy. Merged E state data for the three naturally occurring isotopes in the range v_E = 0–16, expressed in terms of the constants for ⁷⁹Br₂, are (in cm^?1) Y_0,0 = 49 777.962(54), Y_1,0 = 150.834(22), Y_2,0 = ?0.4182(28), Y_3,0 = 6.6(11) × 10^?4, Y_0,1 = 4.1876(28) × 10^?2, Y_1,1 = ?1.607(16) × 10^?4, and Y_0,2 = 1.39(39) × 10^?8. The bond distance is $\text{r}{}_{\mathrm{<mtext>e</mtext>}}\text{= 3.194}\text{A}\text{?}$, and the diabatic dissociation energy to $\text{Br}{}^{\mathrm{+}}\text{(}{}^3\text{P}{}_2\text{) +}\text{Br}{}^{\mathrm{?}}\text{(}{}^1\text{S}{}_0\text{)}\text{is 34 700 cm}{}^{\mathrm{?1}}$.     

The bending vibration bands ν4 and ν5 of HCCI

The bending vibration bands ν₄ and ν₅ of HCCI were studied. From the observed rotational structure the rotational constant B₀ and the centrifugal distortion constant D₀ were obtained. The results were B₀ = 0.105968(7) cm^?1 and D₀ = 1.96(7) × 10^?8 cm^?1 from ν₄ and B₀ = 0.105948(8) cm^?1 and D₀ = 1.96(11) × 10^?8 cm^?1 from ν₅. The structure of the hot bands 2ν₅(Δ) ← ν₅(Π) and 3ν₅(φ) ← 2ν₅(Δ) was also resolved and hence the values α₅ = ?3.033(8) × 10^?4 cm^?1 and q₅ = 9.3(3) × 10^?5 cm^?1 could be derived. The other most intense hot bands following ν₅ could be explained in terms of the Fermi diads $\text{ν}{}_3\text{2ν}{}_5{}^0$ and $\text{ν}{}_3\text{+}\text{ν}{}_5{}^{\mathrm{\pm 1}}\text{3ν}{}_5{}^{\mathrm{\pm 1}}$. Of the numerous hot bands accompanying ν₄, only those between different excited states of ν₄ could be assigned. Then estimates for α₄ and q₄ were also obtained. In addition, several vibrational constants were derived.     

The ground state of methane 12CH4 through the forbidden lines of the ν3 band

High resolution spectra of the ν₃ band of methane, ¹²CH₄, were recorded by using a “third generation vacuum Fourier interferometer”; a large pressure range (from 0.009 to 10 Torr) with a sample path fixed at eight meters was used, enabling observation of transitions with intensity ratios as low as $\text{1}\text{10 000}$. More than 350 forbidden transitions of the ν₃ band, including about 125 transitions of the Q⁺ branch, were unambiguously identified. Of the 277 transitions retained for computations, one-hundred have 11 ≤ J ≤ 16. From combination difference relations using pairs of transitions having the same upper state energy level (forbidden-allowed and forbidden-forbidden pairs were used), 276 independent differences between ground state energy levels could be determined with uncertainties of about 0.001 cm^?1.These data yielded the following values for the ground state structure constants of ¹²CH₄ along with their standard deviations (in cm^?1): $\text{β}{}^{\mathrm{o}}\text{hc}\text{=5.2410356±0.0000096}$, $\text{γ}{}^{\mathrm{o}}\text{hc}\text{=(?1±0.00074) 10}{}^{\mathrm{?4}}$, $\text{π}{}^{\mathrm{o}}\text{hc}\text{=(5.78±0.18) 10}{}^{\mathrm{?9}}$, $\text{?}{}^{\mathrm{o}}\text{hc}\text{=(?1.4485±0.0023) 10}{}^{\mathrm{?6}}$, $\text{?}{}^{\mathrm{o}}\text{hc}\text{=(1.768±0.126) 10}{}^{\mathrm{?10}}$, $\text{ξ}{}^{\mathrm{o}}\text{hc}\text{=(?1.602±0.067) 10}{}^{\mathrm{?11}}$, Thus, for the first time, the scalar constant π⁰ has been evaluated and ir values have been obtained for the two tetrahedral constants ?⁰ and ξ⁰; furthermore, these values are in very good agreement with the ones recently determined from radiofrequency data, i.e., in cm^?1: $\text{?}{}^{\mathrm{o}}\text{hc}\text{=(?1.45061±0.00014) 10}{}^{\mathrm{?6}}$, $\text{?}{}^{\mathrm{o}}\text{hc}\text{=(1.7634±0.0068) 10}{}^{\mathrm{?10}}$, $\text{ξ}{}^{\mathrm{o}}\text{hc}\text{=(?1.5432±0.0040) 10}{}^{\mathrm{?11}}$ From these values, the 276 differences can be reproduced with an overall rms deviation equal to 0.0009 cm^?1.Finally, the ground state energies of ¹²CH₄ have been calculated for J ≤ 16.     

Cross sections for the quenching of the excited strontium state (51P1) measured in CO/N2O flames

The quantum efficiency of fluorescence, Y, of the 4607.33 Å Sr line $\text{(}{}^1\text{P}{}_1\text{?}{}^1\text{S}{}_0\text{transition}\text{)}$ was measured in four pre-mixed, laminar, shielded CO/N₂O flames of about 2700 K, with different quantitative compositions at 1 atm. From these data, the specific quenching cross sections for O₂, CO₂, CO and N₂ were found to be (152±20 Ų), (30±5 Ų), (49±8 Ų) and (16±3 Ų), respectively.     

Inclusive production of Ξ+ and Ξ− in K+ p interactions at 32 GeV/c

The inclusive production of $\text{Ξ}{}^{\mathrm{+}}$ and Ξ^? hyperons is investigated in K⁺ p interactions at 32 GeV/c. The production cross sections, 36.4±9 μb for the $\text{Ξ}{}^{\mathrm{+}}$ and 6.5±3 μb for the Ξ^?, are rising strongly with energy similarly to $\text{Λ}$ and Λ production in K⁺ p interactions. The $\text{Ξ}{}^{\mathrm{+}}$ are produced preferentially in the forward direction in the c.m.s., while the Ξ^? are produced dominantly backwards. The average transverse momenta and 〈p_T〉_Ξ^?=0.58±0.09 GeV/c.     

Results on the production cross sections π−p → neutrals and π− p→ χ↳2γ0n at 3.8, 6, 8 and 12 GeV/c

The ratio between the cross sections for the reactions $\text{π}{}^{\mathrm{?}}\text{p→}\text{χ}\text{?}{}_{\mathrm{2\gamma }}{}^0\text{n}$ and π^?p → η_→2γ n has been measured to be (2.4 ± 0.9) × 10^?2, (2.1 ± 0.6) × 10^?2 and (2.8 ± 1.3) × 10^?2 at 3.8,6,8 and 12 GeV/c incident momentum respectively.At the same momenta the cross section for π^t- p → neutrals is (1.48 ± 0.09) mb, (0.86 ± 0.05) mb, (0.64 ± 0.04) mb and (0.42±0.03) mb.     

Determination of molecular constants of nitric oxide from (1-0), (2-0), (3-0) bands of the 15N16O and 15N18O isotopic species

The (1-0), (2-0), and (3-0) transitions of ¹⁵N¹⁶O and ¹⁵N¹⁸O are investigated. The wavenumbers of the rotation-vibration lines are reported for the overtone bands and the ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{-}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ (1-0) subband. It is shown that in the data reduction it is advantageous to calculate first merged spectroscopic constants ignoring the Λ-type doubling. The vibrational constants ω_e, ω_ex_e, ω_ey_e and the vibrational dependence of the rotational constants are determined. The study of ¹⁵N¹⁸O allows the determination of the equilibrium values of the centrifugal distortion correction A_De to the spin-orbit constant and of the spin-rotation constant γ_e from the isotopic invariance of the ratios $\text{A}{}_{\mathrm{<mtext>De</mtext>}}\text{B}{}_{\mathrm{<mtext>e</mtext>}}$ and $\text{γ}{}_{\mathrm{<mtext>e</mtext>}}\text{B}{}_{\mathrm{<mtext>e</mtext>}}$. It is found that $\text{A}{}_{\mathrm{<mtext>De</mtext>}}\text{B}{}_{\mathrm{<mtext>e</mtext>}}\text{= (?3.9 ± 1.3) × 10}{}^{\mathrm{?6}}$ and $\text{γ}{}_{\mathrm{<mtext>e</mtext>}}\text{B}{}_{\mathrm{<mtext>e</mtext>}}\text{= (?4.00 ± 0.05) × 10}{}^{\mathrm{?3}}$.     

Oscillator strengths in the Cameron system of carbon monoxide

Relative oscillator strengths in the Cameron system of CO(a³Π ← X¹Σ) have been observed in absorption for six bands (υ′ = 0–5, υ″ = 0) with the result, normalized to the absolute (0, 0) band measurement of Hasson and Nicholls, $\text{?}{}_{00}\text{= (1.62±0.07) × 10}{}^{\mathrm{?7}}$, $\text{?}{}_{10}\text{= (1.96±0.09) × 10}{}^{\mathrm{?7}}$, $\text{?}{}_{20}\text{= (1.41±0.04) × 10}{}^{\mathrm{?7}}$, $\text{?}{}_{\mathrm{3\; 0}}\text{= (0.72±0.03) × 10}{}^{\mathrm{?7}}$, $\text{?}{}_{40}\text{= (0.31±0.02) × 10}{}^{\mathrm{?7}}$, $\text{?}{}_{50}\text{= (0.14±0.01) × 10}{}^{\mathrm{?7}}$. The density of CO was modulated with a motor-driven vacuum valve and synchronous fluctuations (?1 per cent) in the transmitted intensity detected with a lock-in amplifier. Peak pressure in the 21 cm absorption cell was approximately 10 torr. A curve of growth analysis was used to correct saturation effects by less than 3 per cent.     

Baroemf in the metal—superionic-metal system: AgAg4RbJ5Ag

It is shown that the application of pressure to one of the electrodes of the AgAg₄RbJ₅Ag system causes a flow of Ag⁺ ions into a region of lower pressure, thus giving rise to baroemf. The value of the baroelectric coefficient is determined by the volume-to-charge ratio of “metallic” ion: $\text{α =}\text{v}{}_0\text{e}\text{= (8?9) × 10}{}^{\mathrm{?11}}\text{V Pa}{}^{\mathrm{?1}}$, which agrees quite well with the measured values of (7–9) × 10^?11 V Pa^?1. Freshly prepared samples exhibit a non-equilibrium enhancement of baroemf, so that α differs somewhat from the above value.     

Reexamination of the I2 spectrum near the B(3Π0u+) state dissociation limit

The disagreement of Danyluk and King's (Chem. Phys.25, 343 (1977)) rotational constants for levels lying near the dissociation limit of B-state I₂ with the mechanical behavior predicted by near-dissociation theory is investigated. The discrepancies are shown to be much too large to be explained by either the neglect of centrifugal distortion effects in the original analysis or by rotational or spin-rotation coupling to a nearby repulsive 1_u state. These differences are therefore attributed to experimental error, a conclusion which is confirmed by more recent experimental results. A reanalysis of the best available data for levels near the dissociation limit of B-state I₂ then yields improved values for the B-state dissociation limit $\text{D}$ = 20 043.16 (±0.02) cm^?1 of the vibrational index at dissociation v_$\text{D}$ = 87.32 (±0.04) and of the long-range potential constant $\text{C}{}_5\text{= 2.88 (±0.03) × 10}{}^5\text{cm}{}^{\mathrm{?1}}\text{A}\text{?}{}^5$. This in turn implies a slightly improved ground-state dissociation energy of $\text{D}$₀ = 12 440.18 (±0.02) cm^?1.     

Analysis of the Raman spectrum of SF6

The Raman active fundamentals ν₁(A1g), ν₂(Eg), ν₅(F2g), and the overtone 2ν₆ of SF₆ have been investigated with a higher resolution and the band origins were estimated to be: ν₁ = 774.53 cm^?1, ν₂ = 643.35 cm^?1, ν₅ = 523.5 cm^?1, and 2ν₆ = 693.8 cm^?1. Raman and infrared data have been combined for estimation of several anharmonicity constants. The ν₆ fundamental frequency is calculated as 347.0 cm^?1. From the analysis of the ν₂ Raman band, the following rotational constants of both the ground and upper states have been calculated:

$\text{B}{}_0\text{= 0.09111 ± 0.00005}\text{cm}{}^{\mathrm{?1}}\text{; D}{}_0\text{= (0.16±0.08)10}{}^{\mathrm{?7}}\text{cm}{}^{\mathrm{?1}}$

;

$\text{B}{}_2\text{= 0.09116 ± 0.00005}\text{cm}{}^{\mathrm{?1}}\text{; D}{}_2\text{= (0.18±0.04)10}{}^{\mathrm{?7}}\text{cm}{}^{\mathrm{?1}}$

.     

Ni2+ emission in MgO,KMgF3, KZnF3 and MgF2

The emission of Ni²⁺ ions in MgO, KMgF₃, KZnF₃ and MgF₂ crystals has been investigated. The fine structure on the bands at about 20 000 cm^-1 and 13 000 cm^-1 has been studied in detail and from this and the excitation spectra these bands are assigned to ${}^1\text{T}{}_{\mathrm{2g}}\text{→}{}^3\text{A}{}_{\mathrm{2g}}$ and ${}^1\text{T}{}_{\mathrm{2g}}\text{→}{}^3\text{T}{}_{\mathrm{2g}}$ transitions respectively.     

Study of the photon spectrum in the decay KS0→π+π−γ

The branching ratio $\text{Λ(}\text{K}{}_{\mathrm{<mtext>S</mtext>}}{}^0\text{→π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{γ)}\text{Λ(}\text{K}{}_{\mathrm{<mtext>S</mtext>}}{}^0\text{→π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{)}$ has been determined to be (2.68±0.15)×10^?3 for photon energies $\text{E}{}_{\mathrm{\gamma }}{}^1$ greater than 50 MeV in the K_S⁰ rest frame. The decay K_S⁰→π⁺π^?γ is found to be dominated by the internal bremsstrahlung transition. The branching rato of a possible direct transition is found to be less than 0.06 × 10^?3 at 90% confidence level for $\text{E}{}_{\mathrm{\gamma }}{}^1\text{> 50}\text{MeV}$.     

Formation of Xe12 by collision pair absorption at 158 nm

Pair absorption from colliding Xe atoms of the molecular fluorine laser radiation is reported. The absorption coefficient for this process at 300 K was found to be α = (4.32 ± 0.1) × 10^-9Torr^-2cm^-1. Fluorescence at 172 nm originating predominantly from the ${}^1\text{Σ}{}^{\mathrm{+}}{}_{\mathrm{u}}$ state of Xe¹₂ indicates that by this mechanism the Xe dimer laser can be pumped optically.     

High-resolution infrared spectrum of the ν2 and ν8 bands of CH2D2

A high-resolution infrared spectrum of methane-d₂ has been measured in the C-D stretching band region (2025–2435 cm^?1). Rotational structures of the ν₂ and ν₈ bands have been assigned by use of the ASSIGN-diagram method, and the c-type Coriolis interaction between ν₂ and ν₈ has been analyzed. The band origins, ν₂ = 2203.22 ± 0.01 cm^?1 and ν₈ = 2234.70 ± 0.01 cm^?1, the rotational constants and the centrifugal distortion constants for the two bands, and the Coriolis coupling constant, $\text{∥;ξ}{}_{28}{}^{\mathrm{c}}\text{∥; = 0.182 ± 0.015}\text{cm}{}^{\mathrm{?1}}$, have been determined.