3549Mass spectroscopic Knudsen cell studies of the vapor over P4OI0(H) at 150, 315, and 400 OC have shown that P4OIo undergoes a phase transition which lowers the vapor pressure at 300 OC and that the vapor is composed of P4O10, P409, and P408 molecules with an approximate ratio of 10:3:1; furthermore, the decomposition products P408 and P407 showed increased concentration with higher Knudsen cell temperat~res.'~ While species such as P30e7' were produced by 40-eV electron impact, they showed no temperature dependence and were unique to mass spectroscopic studies. The P202-s+ ions were also produced by the electron impact process, as indicated by their high appearance potentials, but they showed increased intensities a t higher temperatures, corroborating the present matrix infrared observation that P40s and P407 are more prone to unimolecular cage decomposition than P4Olo.
ConclusionsThe YAG laser evaporation of hexagonal (molecular) P4Olo produced mainly P4OIo with small yields of the P20s and POz decomposition products. The depolymerization of orthorhombic (covalent network) P4O10 with laser ablation gave a randomized distribution of PO, PO2, P20, P204, and P20s fragmentation (19) (a) Muenow, D. W.; Uy, 0. M.; Margrave, J. L. J. Inorg. Nucl. Chem. 1970, 32, 3459. (b) Hashizume, A.; Wasada, N.; Tsuchiya, T. Bull. Chem. SOC. Jpn. 1966,39, 150.products, where the smaller fragments had high intensities, and little P4O10. The HOP0 and HOP02 molecules were observed as hydrolysis intermediates. Thermolysis of P4Olo at 900-950 "C produced a nonrandomized distribution of depolymerization products, which favored P409 and PO2, and to a lesser extent P4O8. P205, and P2O4.Reactive laser ablation of red phosphorus and oxygen produced the same species as the depolymerization reactions of orthorhombic P4010 and earlier reactions of P2 with O2 and 03.57 The reaction was confined to the plume produced by the laser owing to the production of excited phosphorus fragment species. This work shows that POz is a particularly stable gaseous species20 and suggests that molecular P205 can also be observed in the gas phase.Laser ablation has been used for a number of years with great success in combination with matrix-isolation fluorescence spectroscopy by Bondybey and co-workers2I and for matrix-isolation ESR studies by Knight." This work exploits the combination of laser ablation of polymerized substrates and reactive laser ablation with matrix infrared spectroscopy. (20) Kawaguchi, K.; Saito, S.; Hirota, E.; Ohashi, N.Gas-phase infrared spectra and liquid-phase Raman spectra are presented for 1 -chlorocyclobutene and 1 -fluorocyclobutene. Complete assignments of vibrational fundamentals are proposed for these molecules of C, symmetry. For 1 -chlorocyclobutene (cm-I): (a') . Frequencies of CH-rich modes correlate closely for these isotopomer-like molecules. These results along with a Raman spectrum of liquid cyclobutene near -100 OC have provided evidence for assigning five unsettled vibrational fundamentals of cyclobutene. These modes...