Detecting singly charged ions during field evaporation of tantalum at high temperatures

Abstract

The field evaporation of tantalum from point emitters in a broad range of temperatures from T = 300 to 2500 K was studied using a static magnetic mass spectrometer equipped with a special field ion source. The room-temperature mass spectrum of field-evaporated particles displayed only the peaks of triply charged ions (Ta3+). As the temperature was increased, the charge of field-evaporated ions exhibited a decrease: at T ∼ 1000 K, the peaks of doubly charged ions (Ta2+) prevailed. The peaks of singly charged ions (Ta+) were detected for the first time at temperatures in the interval 1900 K < T < 2500 K. The rate of evaporation of singly charged tantalum ions was several orders of magnitude lower than that of doubly charged ions.