Cesium sputtering technique

During the search for 36C1 at Rochester, 5-13 pA of Cl ions were produced from silver chloride in the cesium sputter source. The detection techniques were basically similar to those discussed for 14C. The samples and the results obtained are given in Table 2. 

The measurements that have been made at Rochester and the experience that has been gathered over the years on the operation of sputter ion sources [38] indicate that an analytical tool of unprecedented sensitivity and accuracy for isotopic ratio determinations can be constructed by coupling SIMS technology with the new accelerator technique. The only difference in principle between the experiments that have been conducted to date and the technique as it would be applied in secondary ion mass spectrometry is that the primary beam of cesium would be focussed to a fine probe of pm dimensions rather than the spot diameters of approximately 1 mm that have been used to date. 

Both oxygen and cesium ion beams are used. The former is more effective with the electropositive elements (i.e., B, Al, Cr, etc.), and the latter with the electronegative elements (i.e., C, O, As, etc.). Since the technique involves sputtering of the surface, depth profiling can be carried out readily. 

In the SIMS technique, an oxygen or cesium ion beam incident on the sample, sputters atoms from the surface. Either negatively or positively charged ions are mass analyzed and their density displayed as a function of sputter time. By using calibration standards, the density is calibrated as concentration/cm, and by measuring the sputter crater depth/ the time axis is converted to a distance axis, giving a dopant concentration vs. depth plot. 

Refactory metal oxides of NbO x, WO x, TaO x, and Silver oxide (AgO x) have been studied for a high performance collector. The metal oxide materials were deposited on metal substrates by RF sputtering in the Ar/0 2 gas mixture, in which the partial pressure of O 2 was deliberately set at the lower values in order to sputter in the stoichiometrically oxygen gas short conditions. Work function of the metal oxides was measured by cesium plasma immersion technique. As results, minimum work function values of each oxide materials were obtained as follows AgO x =1.25eV, NbO x =1.38eV, WO x =1.42eV,... 

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