Spores of Bacillus subtilis lacking all germinant receptors germinate >500-fold slower than wild-type spores in nutrients and were not induced to germinate by a pressure of 100 MPa. However, a pressure of 550 MPa induced germination of spores lacking all germinant receptors as well as of receptorless spores lacking either of the two lytic enzymes essential for cortex hydrolysis during germination. Complete germination of spores either lacking both cortex-lytic enzymes or with a cortex not attacked by these enzymes was not induced by a pressure of 550 MPa, but treatment of these mutant spores with this pressure caused the release of dipicolinic acid. These data suggest the following conclusions: (i) a pressure of 100 MPa induces spore germination by activating the germinant receptors; and (ii) a pressure of 550 MPa opens channels for release of dipicolinic acid from the spore core, which leads to the later steps in spore germination.

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The Raman spectrum of solid nitrogen has been studied at high pressures and low temperatures using a method of sample preparation that allows the separation of effects due to change of molar volume and of temperature, respectively. Two lines have been observed in the lattice region of the γ phase which are identified as Eg and B1g librational modes on the basis of frequency and relative intensity calculations. An asymmetrical line has been observed in the stretching region of this phase. In the α phase, the measured Grüneisen parameters indicate that neither the quadrupolar nor the 6–12 atom–atom interaction potential has the correct volume dependence. The temperature dependence of the frequency and linewidth of the Eg librational mode is proposed to be due to libron–phonon interactions. Two very broad Raman lines are observed in the lattice region of the β phase. The low- and high-frequency lines are identified with translational and librational modes, respectively. The observations are consistent with a precessing molecule model for the β phase.

Absolute Raman cross sections and mode Gruneisen parameters of the Raman-active optical vibrational modes of sapphire (a = Al2O3) were measured. Intensity measurements show that magnitudes of the Raman tensor components agree very well with group theoretical expectations. Pressure dependence of the frequencies has been measured over a range from 1 to 10 kbars and mode Gruneisen parameters have been calculated.

The spectrum of depolarized light scattered from monatomic fluids has been measured as a function of temperature and density over a range extending from the dilute-gas limit to densities as much as 50% above the normal liquid density. The low-density spectra exhibit the nearly exponential character reported earlier. Above ~ 200 amagats the spectra broaden at progressively higher density and exhibit qualitative changes at extremely high densities. Additional spectral-shape changes occur for very high effective temperatures.It has been recently demonstrated that the spectrum of depolarized light inelastically scattered by a monatomic gas can be quantitatively described in terms of the dynamics of the binary collision. 1 * 2 On the other hand, quite similar spectra have been observed in very dense simple fluids (i.e., liquids) wherein the dynamics are certainly not adequately described by binary collisions. 3 * 4 For example, according to the binarycollision model the spectrum should extend over a range of frequencies characterized by the inverse duration of the collision encounter, r" 1 = ^TH/^O J where V TH is the thermal velocity and r 0 the characteristic distance over which two particles influence each other's polarizability. Thus the binary collision model predicts that (1) the spectral width and shape are independent of the fluid density p; (2) the characteristic width should vary as the thermal velocity, or (kT) 1/2 ; and (3) the integrated intensity should increase as p 2 .The experiments of McTague, Fleury, and Du-Pre 3 showed that the intermolecular spectrum in liquid argon was markedly different from that in the vapor at the same temperature and pressure, indicating a clear failure of the above predictions. It is obviously important to understand, at least experimentally, how the differences in the spectra (and thus of the short-time dynamics) evolve in going from the dilute gas to the very densefluid limit. 5 In order to separate temperature and density effects, the spectra should be explored along isochores and isotherms over a wide range. In this paper we report the results of such experiments in the Simple fluids argon and neon.For these experiments we have constructed a high-pressure optical cell capable of operating at temperatures between 4 and 300°K (or above) and at pressures between 100 and 10 000 atm. 6 * 7 The light-scattering apparatus is described elsewhere. 3 Considerable care was taken to insure against molecular impurities by (1) monitoring the Raman positions for 0 2 , N 2 , and C-H vibrations and (2) taking mass spectrometry tests for impurities subsequent to each set of data runs. Low-frequency rotational bands from such impurities can severely distort the intermolecular spectrum. In fact neon is so weak a scatterer that -100 ppm of molecular impurities will completely dominate the low-frequency spectrum.Our data are presented in the form of logarithmic plots of the scattered intensity against a scale linear in frequency. For a purely exponential spectrum, a simple characteristic freq...

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