Ferris J P, Khwaja H
Department of Chemistry, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA.
Icarus. 1985;62:415-24. doi: 10.1016/0019-1035(85)90184-8.
Photolysis of NH3-PH3 mixtures (11 Torr) at 175 degrees K resulted in the same initial rate of P2H4 formation as when the 11 Torr of pure PH3 was photolyzed. A higher yield of P2H4 is obtained at 175 degrees K than at 298 degrees K because some of the P2H4 condenses on the cell wall at 175 degrees K and is not subject to further reaction. Some reaction of P2H4 is taking place as observed by the decrease in its yield and on the formation of red phosphorus on extended photolysis of PH3 at 175 degrees K. No NH2PH2 or (PN)x were detected as photoproducts as indicated by the absence of change in the UV spectral properties of the P2H4 and red phosphorus fraction, respectively, when HN3 is present. Although the pathway for PH3 decomposition is changed, the outcome of the photochemical process is essentially the same in the absence or presence of NH3. The formation of P2H4 and red phosphorus was not inhibited by small amounts of C2H4 and C2H2, so the low levels of hydrocarbons on Jupiter and Saturn will not have a significant effect on the course of PH3 photolysis. The ratio of products of PH3 photolysis are only slightly affected by the wavelength of light used. Use of a xenon lamp, with a continuous emission in the ultraviolet where P2H4 absorbs, results in only a modest decrease in the yield of P2H4 and a modest increase in the rate of formation of red phosphorus as compared to the rates observed with a 206.2-nm light source. The quantum yield for P2H4 formation is pressure independent in the 0.5-11 Torr range. This quantum yield is not affected by lowering the temperature to 157 degrees K or by the addition of 100 Torr of H2. It is concluded that photolysis of PH3 to P2H4 and the subsequent conversion of P2H4 to red phosphorus are likely processes on Jupiter and Saturn and that particles of P2H4 condense in the atmospheres of these planets. The conversion of some of the P2H4 to red phosphorus may take place on Jupiter.
在175K下对NH₃ - PH₃混合物（11托）进行光解，生成P₂H₄的初始速率与对11托纯PH₃进行光解时相同。在175K下获得的P₂H₄产率高于298K时，因为在175K时一些P₂H₄会凝结在细胞壁上，不再发生进一步反应。正如通过P₂H₄产率的降低以及在175K下对PH₃进行长时间光解时红磷的形成所观察到的那样，P₂H₄正在发生一些反应。当存在HN₃时，分别通过P₂H₄和红磷部分的紫外光谱特性没有变化表明，未检测到NH₂PH₂或(PN)ₓ作为光解产物。尽管PH₃分解的途径发生了变化，但在不存在或存在NH₃的情况下，光化学过程的结果基本相同。少量的C₂H₄和C₂H₂不会抑制P₂H₄和红磷的形成，因此木星和土星上低水平的碳氢化合物不会对PH₃光解过程产生显著影响。PH₃光解产物的比例仅受到所用光波长的轻微影响。与使用206.2纳米光源观察到的速率相比，使用在P₂H₄吸收的紫外区域有连续发射的氙灯，只会使P₂H₄的产率适度降低，红磷的形成速率适度增加。在0.5 - 11托范围内，P₂H₄形成的量子产率与压力无关。将温度降至157K或添加100托的H₂不会影响该量子产率。可以得出结论，在木星和土星上，PH₃光解为P₂H₄以及随后P₂H₄转化为红磷是可能发生的过程，并且P₂H₄颗粒会在这些行星的大气中凝结。在木星上可能会发生一些P₂H₄向红磷的转化。
