Abstract The molecular and ionic sublimation of neodymium, dysprosium, holmium, and erbium triiodides was studied by Knudsen effusion mass spectrometry. The monomer LnI3, dimer Ln2I6, and trimer Ln3I9 molecules and the ions LnI4– and Ln2I7– were found to be constituents of the saturated vapors in each case. The partial pressures of the vapor species and the equilibrium constants of the ion-molecular reactions were calculated. On the basis of a joint analysis of all literature data, the sublimation enthalpies ΔsHo(298.15 K)/(kJ∙mol–1) are recommended as 293±3 (NdI3), 387±30 (Nd2I6), 281±3 (DyI3), 353±12 (Dy2I6), 281±3 (HoI3), 352±6 (Ho2I6), 278±4 (ErI3), and 350±30 (Er2I6). The standard formation enthalpies ΔfHo(298.15 K)/(kJ∙mol–1) of the molecules and ions were determined to be –346±5 (NdI3), –891±30 (Nd2I6), –815±23 (NdI4–), –1379±46 (Nd2I7–), –336±4 (DyI3), –880±12 (Dy2I6), –811±23 (DyI4–), –1360±46 (Dy2I7–), –342±4 (HoI3), –894±7 (Ho2I6), –814±23 (HoI4–), –1372±46 (Ho2I7–), –341±5 (ErI3), –888±30 (Er2I6), –819±23 (ErI4–), and –1377±46 (Er2I7–).

中文翻译：

---

钕、镝、钬和三碘化铒的分子和离子升华以及分子和离子的热化学

摘要 采用克努森渗出质谱法研究了钕、镝、钬和三碘化铒的分子和离子升华。发现单体 LnI3、二聚体 Ln2I6 和三聚体 Ln3I9 分子以及离子 LnI4– 和 Ln2I7– 在每种情况下都是饱和蒸汽的成分。计算了蒸气物质的分压和离子-分子反应的平衡常数。在对所有文献数据进行联合分析的基础上，升华焓 ΔsHo(298.15 K)/(kJ∙mol–1) 推荐为 293±3 (NdI3)、387±30 (Nd2I6)、281±3 (DyI3) )、353±12 (Dy2I6)、281±3 (HoI3)、352±6 (Ho2I6)、278±4 (ErI3) 和 350±30 (Er2I6)。分子和离子的标准形成焓 ΔfHo(298.15 K)/(kJ∙mol–1) 确定为 –346±5 (NdI3), –891±30 (Nd2I6), –815±23 (NdI4–) , –1379±46 (Nd2I7–),