Ultrasonic Relaxation in Methylene Chloride

Ultrasonic relaxation and the vibrational specific heat of liquid sulphur dioxide

“…Perhaps the most important result of the present investigation is th a t the two regions of dispersion observed in gaseous sulphur dioxide by Lambert & Salter (1957) are also found in the liquid. The same pattern of behaviour has previously been established for methylene chloride vapour (Sette et al 1955) and liquid (Andreae 1957). The remarkable similarity in behaviour between these two com pounds is discussed in the two companion papers (Lambert & Salter 1957;Dickens & Linnett 1957).…”

“…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.…”

“…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). These results are in accordance with the conclusions reached from the observed dispersion in the vapour phase, but in the latter case the experimental recordings extend over both regions of dispersion (Sette, Busala & Hubbard 1955).…”

A survey of the geophysical properties of chlorinated DNAPLs

“…Direct measurements of velocity dispersion in pure liquids are relatively rare, particularly for low frequencies, but existing data suggests that the frequency dependence of acoustic velocity in pure chlorinated solvents is almost insignificant below 50 MHz. Andreae (1957) provides velocity dispersion data from a variety of sources for methylene chloride between 7.54 and 209 MHz at 25 8C. Over the decade from 7.54 to 70 MHz he observed a change in velocity of only 5 m/s.…”