A MODIFICATION OF THE IONIZATION METHOD ESPECIALLY SUITABLE FOR CONTINUOUSLY REC0RDIN6 CONTACT POTENTIAL DIFFERENCES

摘要

Ions formed in the air space between two different conducting surfaces will migrate in the electric field and produce a current in an external circuit proportional to the contact potential difference. Since the ionization method of measuring contact potential involves a direct-current output, it is more adaptable for continuous recording than are other methods, such as the vibrating condenser method. A study was made of the factors which minimize the inherent errors of the ionization method and of a modification which permits the use of an or dinar y low-impedance-input dc chart-type voltmeter and the use of a wide air spacing desirable for certain applications. The modification is an accounting for errors introduced by a w i d e spacing between the ionizing source and the surface being studied, the wide spacing causing the air-space impedance to be comparable to the impedance of the indicating meter. In comparing the vibrating condenser method and the ionization method it was determined that in those cases where gaseous adsorption is not a factor the ionization method did show much greater sensitivity as well as permit continuous dc voltmeter recording.