scispace - formally typeset

Journal ArticleDOI

Electric Dipole Moments of Several Molecules from the Stark Effect

01 Feb 1953-Journal of Chemical Physics (American Institute of Physics)-Vol. 21, Iss: 2, pp 308-310

AbstractThe following molecular electric dipole moments, in Debye units, have been obtained from the Stark effect of pure rotational spectra observed in the microwave region: 0.234±0.004 for NF3; 1.03±0.01 for PF3; 1.77±0.02 for POF3; 3.00±0.02 for HCN; 3.92±0.06 for CH3CN; 3.83±0.06 for CH3NC; 1.79±0.02 for CH3F; 0.75±0.01 for CH3CCH; 1.26±0.01 for SiF3H. All values apply to the ground vibrational state.

...read more


Citations
More filters
Book ChapterDOI
Abstract: Publisher Summary This chapter discusses molecular refractivity and polarizability. Refractive indices ( n ) of pure substances are more accurately measurable than any other optical properties. The refractive index of a substance varies with its physical state, temperature t , and wave-length λ of the light by which n is observed. The first two of these effects are attributed to the density d . The specific refraction r of a substance multiplied by the molecular weight is referred as molecular refraction. Polarizability of a particle is defined as the dipole moment induced by an electric field of unit intensity. The polarizabilities of monatomic ions and molecules are generally independent of field direction. The principal polarizabilities of molecules can be analyzed in terms of anisotropic bond polarizabilities. Polarizabilities are also responsible for the birefringence, which appears whenever the orientations of anisotropic molecules in an assemblage are derandomized or changed by any disturbing force.

343 citations

Journal ArticleDOI
Abstract: Organophosphorverbindungen werden auf zweierlei Art in der Synthesechemie eingesetzt: Entweder dienen sie als Hilfsreagentien wie etwa bei der Wittig-Reaktion, oder sie werden selbst in die Zielmolekule eingebaut. Gerade das zweite Anwendungsfeld hat sich durch die Herstellung niederkoordinierter Phosphorverbindungen in den letzten Jahren enorm erweitert. Zu den niederkoordinierten Phosphorverbindungen zahlen auch Phosphaalkine, die im Mittelpunkt dieses Beitrags stehen und viel Interesse sowohl bei Organikern als auch bei Anorganikern gefunden haben. Der Einbau der PCR-Einheit in Heterocyclen, in Phosphaarene und deren Valenzisomere sowie in polycyclische Verbindungen, die Verwendung als neue Ligandensysteme in der Komplexchemie und schlieslich die Cyclooligomerisierung mit Organometallreagentien belegen dies auf eindrucksvolle Weise. Phosphaalkine haben bezuglich ihrer Reaktivitat wenig mit Nitrilen gemeinsam, zeigen aber um so mehr Verwandtschaft mit den isoelektronischen Alkinen.

149 citations

Journal ArticleDOI
Abstract: The Stark effect has been observed in the microwave rotational spectra of PH3 and PD3 at 1.1 and 2.1 mm wavelength, respectively, in DI127 at 1.5 mm, and in C12O16 at 2.6 mm. The J = 1→2 transition of PD3 has been observed at 1.08 mm. Analysis of the data yields values of the electric dipole moment, μ, as follows: PH3, 0.578±0.010 debye; DI, 0.316±0.010 debye; and CO, 0.112±0.005 debye. The centrifugal stretching constants, DJ and DJK, for PD3 are found to be 0.800 Mc and 1.31 Mc, respectively.

128 citations

Journal ArticleDOI
Abstract: From high precision measurements of first- and second-order Stark effects on both ΔM = 0 and ΔM = ±1 transitions, the molecular dipole moments of normal and deuterated methyl fluoride and methyl cyanide have been obtained as follows: for CH3F, μ = 1.8572 ± 0.0010 D; for CD3F, μ = 1.8682 ± 0.0010 D; for CH3CN, μ = 3.913 ± 0.002 D; for CD3CN, μ = 3.919 ± 0.004. A remeasurement of zero-field lines yields more accurate values of the spectral constants for three of these. They are: for CH3F, B0 = 25 536.148 ± 0.005 Mc/sec, DJ = 60.4 ± 0.10 kc/sec, DJK = 439.26 ± 0.05 kc/sec; for CD3F, B0 = 20 449.854 ± 0.012 Mc/sec, DJ = 34.2±0.4 kc/sec, DJK = 221.7 ± 0.9 kc/sec; for CD3CN, B0 = 7858.117 ± 0.008 Mc/sec, DJ = 4.64 ± 0.06 kc/sec, DJK = 110.59 ± 0.10 kc/sec.

115 citations


References
More filters
Journal ArticleDOI

141 citations

Journal ArticleDOI
TL;DR: A microwave spectrograph is described in which the absorption of the gas being studied is modulated by the application of a periodic Stark‐effect field so that the output of the crystal detector contains a radiofrequency component which can be amplified with a narrow‐band amplifier.
Abstract: A microwave spectrograph is described in which the absorption of the gas being studied is modulated by the application of a periodic Stark‐effect field so that the output of the crystal detector contains a radiofrequency component which can be amplified with a narrow‐band amplifier. By using a very narrow band‐width, achieved by employing phase‐sensitive detection, high sensitivity is obtained. The klystron is swept mechanically over the frequency range. Details of the components are given.

101 citations