The currents (
J− and
I−) of thermal electron (e
−) and ion (H
−) desorbed from heated powdery SrH
2 were simultaneously measured by mass spectrometry as a function of the sample temperature, introduced H
2 gas pressure or time elapsing after increasing temperature, introducing H
2 or stopping the introduction. Analysis of the data thus obtained yields the notable results as follows. (1) Above
![](/images/glyphs/BQ1.GIF)
800K, those active spots (Sr) with low work function (
φ) is created by such a thermal decomposition as
SrH2→Sr+H2. (2) From the spots, not only e
− but also H
− is desorbed even without introducing H
2. (3) By introducing H
2 up to
5×10−4Torr,
φ is increased by up to
![](/images/glyphs/BQ1.GIF)
0.3eV according to a deactivation reaction
(Sr+H2→SrH2). (4) By this increase,
J− is decreased to less than 1/10 but
I− is increased up to
![](/images/glyphs/BQ1.GIF)
2.4 times. In conclusion, H
− is thermally produced not only from the H constituent of powdery SrH
2 kept above
![](/images/glyphs/BQ1.GIF)
800K but also from the H
2 introduced onto the hydride, in spite of low electron affinity of hydrogen.