Ultrasonic Relaxation and the Vibrational Specific Heat of Carbon Disulphide

Ultrasonic relaxation and the vibrational specific heat of liquid sulphur dioxide

“…A comparison of the present results with those previously obtained for carbon disulphide (Andreae et al 1956) and methylene chloride (Andrea th at the relaxation in sulphur dioxide also involves either part, or the whole, of the vibrational specific heat. I t remains to show th at the experimental value for the relaxing specific heat can be related in a convincing way to the different contribu tions to the specific heat as calculated from spectroscopic data.…”

“…I t follows th at the effect of the velocity dispersion on the observed relaxation in liquid sulphur dioxide is practically negligible since r is less than 0-02 throughout the temperature range covered in the experiments. A different case arises in the vibrational relaxations reported in carbon disulphide (Andreae et al 1956) and methylene chloride (Andreae 1957), where the analysis of the experi mental results was carried out in steps of successive approximation in order to account for the dispersion in velocity. This more laborious procedure can now be replaced by a simple application of equation (A 15) which has been used in assessing the results of the present investigation.…”

“…Only a few examples of vibrational relaxation in liquids are known, and this is principally due to the fact th at the expected region of relaxation falls at frequencies higher than it has yet been possible to reach experi mentally. I t has been shown th at the anomalous absorption of ultrasonic waves in (liquid) carbon disulphide is due to a relaxation of the total vibrational specific heat, which is described by a single relaxation time (Andreae, Heasell & Lamb 1956). In liquid methylene chloride the observed relaxation can be accounted for by the specific heat associated with all the vibrational modes except the mode of lowest wave number which is expected to give rise to a relaxation at higher ultrasonic frequencies (Andreae 1957).…”

CHAPTER 12. Ultrasonics 1: Speed of Ultrasound, Isentropic Compressibility and Related Properties of Liquids

“…Experimental results suggest that the absorption above the classical value is due to vibrational relaxation only, and that the total vibrational heat capacity relaxes at one frequency. For liquid carbon disulfide at 298.15 K, the observed relaxation is centred at about 78 MHz, 30 and the dispersion of the speed of sound obtained therefrom is about v 2 1 v 2 0 % 1:08. For such a liquid, the primary effect of increasing the hydrostatic pressure is a decrease in the free volume, which in turn leads to an increase in the rate of molecular collisions.…”

Use of an intracavity spatial filter for reducing the divergence of excimer laser radiation

“…Biquard (1936), Libermann (1949), Huddart (1950), Pinkerton (1951 anc Karpovich (1954). A probable explanation for these effects has been put forwart by de Groot and Lamb (1955).…”