The condensation produced in supersonic expansions of $\mathrm{C}{\mathrm{O}}_2$ is studied quantitatively combining Rayleigh and Raman scattering. The cluster number density $n_c$ and the mean cluster size $\overline{N}$ are obtained for five expansions with stagnation pressures $P_0=1–5\text{bars}$, and temperature $T_0=294\mathrm{K}$, along axial and radial directions; $n_c$ and $\overline{N}$ are determined from the condensation onset up to a terminal size ${\overline{N}}_{\infty }$, verifying the empirical law ${\overline{N}}_{\infty }\propto P_0^{2.23}$. A maximum growth rate $d\overline{N}∕dt\approx 8\times {10}^8{\mathrm{s}}^{-1}$ is estimated for the $5\text{−}\text{bar}$ expansion. The Raman spectra show a coexistence of solid and liquidlike phases in the jet, with a progressive transition from the liquid to the solid fraction as the clusters increase their size.

• Received 26 July 2005

DOI:https://doi.org/10.1103/PhysRevA.72.053204