抄録
Ionization efficiency curves have been measured for the ions produced from C2D2 by monoenergetic electron impact over ranges of about 10 eV near their appearance thresholds. The breaks in the total ionization efficiency curve were found to correspond to the ionic and autoionizing states of C2D2. The curve was reproduced by using a simulation technique, and the degrees of contribution from those states to the total ion intensity were estimated. The total contribution from all autoionizing states was found to reach 40% near 16 eV. This degree of C2D2 is higher than that of C2H2 below 20 eV. No indication of isotope effect was found on the appearance potentials of the fragment ions.
