摘要:

A method has been devised for accurate determination of the absolute rate of sputtering, i.e., the measurement of the number of atoms liberated from a metallic target under the impact of a single ion of known energy. The accuracy of this measurement was 6 to 7 percent—a precision hereto unattainable by other methods. The apparatus producing argon ions consisted of a strong ion‐source of capillary‐arc type. The ions were accelerated within a high vacuum chamber through a potential, which was varied from 2000 to 7000 volts, and then allowed to strike a metallic target. The sputtering rate was determined by measuring the positive ion current to the target and the loss of target material. Results are given on sputtering of silver by argon, and on the secondary electron emission from aluminum and molybdenum.

ISSN:0021-8979    

DOI:10.1063/1.1712854

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

Using C11as tracer for the study of carbon dioxide absorption in plants, unexpected analytical difficulties were encountered. However, a satisfactory technique was developed for the rapid measurement of radioactivity in liquid samples. A degree of precision was obtained so that after the elapse of 6 half‐lives (2 hours) the sum of the activities taken from the reaction system was accurate to 1 or 2 percent. This required the determination of an accurate half‐life value for C11(20.35 min.). The experimental procedures are described.

ISSN:0021-8979    

DOI:10.1063/1.1712855

出版商:AIP    

年代:1941

数据来源: AIP