Pyrolysis pathways and kinetics of thermal decomposition of diethylzinc and diethyltellurium studied by mass spectrometry

Abstract

The thermal decomposition of diethylzinc (Et₂Zn) and diethyltellurium (Et₂Te) has been studied both separately and combined using an isothermal reactor attached to a quadrupole mass spectrometer (QMS). Under helium and hydrogen atmospheres the decomposition of Et₂Zn leads to ethene, ethane and n-butane; with D₂ as a carrier gas C₂H₅D is produced. Pyrolysis of Et₂Te leads to ethane and ethene only. With helium as the carrier gas, the activation energy for the pyrolysis was E ≈ 52 kcal mol^–1 for Et₂Zn and E ≈ 50 kcal mol^–1 for Et₂Te, firstorder kinetics being assumed. Under a hydrogen atmosphere, the determination of the activation energy for the pyrolysis of Et₂Zn was inaccurate with a first-order reaction rate, and the activation energy for the pyrolysis of Et₂Te was reduced to E ≈ 47 kcal mol^–1. In the co-pyrolysis, which is close to the conditions of ZnTe growth, the principal trends are enhancement of Et₂Te decomposition and an increase of the thermal stability of Et₂Zn.