Substituted Methanes. III. Raman Spectra, Assignments, and Force Constants for Some Trichloromethanes

Zietlow, James P.; Cleveland, Forrest F.; Meister, Arnold G.

doi:10.1063/1.1747862

Cited by 53 publications

(7 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This may result from a partial F ermi resonance with the very intense W 68. The Vl<' frequency shows a + 17 cml shift from the liquid value found in the Raman effect [9] .…”

Section: 9 Cfc13mentioning

confidence: 64%

Infrared spectra of eighteen halogen-substituted methanes

Plyler¹,

Benedict²

1951

J. RES. NATL. BUR. STAN.

161

View full text Add to dashboard Cite

In order to s t ud y how the vibratio nal freq uenci es of methane vary with haloge n substit utions, the infrared spectra of the following halo g~n-s ub stit u te d methanes . have been st udied with a prism spectrometer between 2 and 38 mICrons: Carbon tetraflu onde, chlorot rifiuoromethan e dichlorodifiuoromethane trichlorofiuorom ethane, car bo n tet rach lorid e, trichlorobromom~than e, dichlorodibromol~ethane , fiuoroform, di~uoroch l o romet h an e, dichlorofluoromethane chloroform di chlorobromomethane, chlorodlbromomethalle , bromoform , iodoform, me th ylene flu orid e, methylene. chloride, and m~th~l ene iodide. Spectra are prese nted as obtained at room temperature ll1 t he vapor and lIquid states, an d l.n a f ew cases in sol ut ion. The bands are interpreted as fundam entals, overtones, combmatlO n, and differe nce bands. Tables and grap hs display t he regularities existing among t he various fundam entals of these molecules and other haloge n-subst ituted methanes. Force-constant calculat ions, using an approximate potential function with ge neral constants transferred from one molec ul e to another a re reported.

show abstract

“…This may result from a partial F ermi resonance with the very intense W 68. The Vl<' frequency shows a + 17 cml shift from the liquid value found in the Raman effect [9] .…”

Section: 9 Cfc13mentioning

confidence: 64%

Infrared spectra of eighteen halogen-substituted methanes

Plyler¹,

Benedict²

1951

J. RES. NATL. BUR. STAN.

161

View full text Add to dashboard Cite

show abstract

“…[25][26][27][28][29] Both CCl 4 and CHCl 3 have a number of lower energy vibrational modes than the initially excited mode at ϳ1980 cm Ϫ1 . 30,31 CHCl 3 also has a CH stretching mode at higher energy, ϳ3020 cm Ϫ1 , which is too high in energy to participate in the vibrational dynamics. In Fig.…”

Section: Discussionmentioning

confidence: 99%

The low frequency density of states and vibrational population dynamics of polyatomic molecules in liquids

Moore

Tokmakoff

Keyes

et al. 1995

The Journal of Chemical Physics

111

View full text Add to dashboard Cite

Instantaneous normal mode calculations of the low frequency solvent modes of carbon tetrachloride ͑CCl 4 ͒ and chloroform ͑CHCl 3 ͒, and experiments on the vibrational population dynamics of the T 1u CO stretching mode ͑ϳ1980 cm Ϫ1 ͒ of tungsten hexacarbonyl in CCl 4 and CHCl 3 are used to understand factors affecting the temperature dependence of the vibrational lifetime. Picosecond infrared pump-probe experiments measuring the vibrational lifetime of the T 1u mode from the melting points to the boiling points of the two solvents show a dramatic solvent dependence. In CCl 4 , the vibrational lifetime decreases as the temperature is increased; however, in CHCl 3 , the vibrational lifetime actually becomes longer as the temperature is increased. The change in thermal occupation numbers of the modes in the solute/solvent systems cannot account for this difference. Changes in the density of states of the instantaneous normal modes and changes in the magnitude of the anharmonic coupling matrix elements are considered. The calculated differences in the temperature dependences of the densities of states appear too small to account for the observed difference in trends of the temperature dependent lifetimes. This suggests that the temperature dependence of the liquid density causes significant changes in the magnitude of the anharmonic coupling matrix elements responsible for vibrational relaxation.

show abstract

“…4 Such gradients may be expected to occur during chemical reactions going on in closed vessels 5 when the usual processes of temperature equilibration, convection, and conduction are insufficiently fast to compensate for temperature changes arising from the heat of the reaction. 6 These problems are, as we shall see, usually negligible in flow systems because of the flow velocities employed. 6 In the following sections I shall first calculate the approximate gradients which may be expected in "slow" 52,1129 (1948) has made similar calculations of the temperature gradients in liquid systems arising from improper attainment of temperature equilibrium across the walls of a reaction vessel at the start of the reaction.…”

Section: Introductionmentioning

confidence: 89%

“…Because of the large temperature coefficients of most reactions (35 percent per percent change in T), temperature gradients of as little as 1°C across a reaction vessel can cause a 5-percent error in measurements of the rate constant and even greater errors in estimations of the activation energies of the reaction. 6 It is generally assumed that the effects of such small temperature gradients will tend to cancel in making comparisons of the rate constants. 6 These problems are, as we shall see, usually negligible in flow systems because of the flow velocities employed.…”

Section: Introductionmentioning

confidence: 99%

Temperature Gradients in Reacting Systems

Benson

1954

The Journal of Chemical Physics

View full text Add to dashboard Cite

A study of the heat conduction equation for reactions going on in a spherical flask leads to a calculation of three parameters, 1" the mean lifetime for the establishment of stationary states, AT m the maximum temperature difference between the walls of the vessel and the reacting gas, and the average temperature difference (AT m)Av. These are given by pCvr02 RHr02in which p is the density, Cv the specific heat at constant volume, ro the radius of the vessel, K the coefficient of thermal conductivity, R the specific rate of reaction, and H the heat of reaction.In liquid systems under usual conditions 1" is of the order of r02 minutes (ro in cm) while (AT m)Av is about ±O.2°C (for H = ±1O kcal, half-life = 1 hour, ro= 5 cm) so that such effects are usually negligible. In gases on the other hand (AT m)Av can be of the order of magnitude of 2°C or higher depending on the various conditions, resulting in significant errors in observed rate constants and activation energies. The effects of added inert gases, pressure, vessel packing, and other parameters are discussed. A very crude treatment of convection shows that it is not expected to alter appreciably the magnitude of (AT m)Av.

show abstract

Substituted Methanes. III. Raman Spectra, Assignments, and Force Constants for Some Trichloromethanes

Cited by 53 publications

References 43 publications

Infrared spectra of eighteen halogen-substituted methanes

Infrared spectra of eighteen halogen-substituted methanes

The low frequency density of states and vibrational population dynamics of polyatomic molecules in liquids

Temperature Gradients in Reacting Systems

Contact Info

Product

Resources

About