The Mass Difference Measurement of(12C21H4-12C16O), (12C2 1H4-14N2), (14N2-12C16O)and(12C21H4-12C22D2)Doublets

Abstract

The mass differences of(C2H4-CO), (C2H4-N2), (N2-CO)and(C2H4-C2D2)doublets have been measured. The apparatus used is the reconstructed large mass spectroscope of double focusing type with the cylindrical electric field(φe=84°50', ae=1092mm)and the uniform magnetic field(φm=60°, am=1200mm). The dimensions of main parts of this apparatus are quite similar to the old one destroyed by the high-tide typhoon in1961. The half-width resolution of about300, 000is obtained at routine operating condition(the slitwidth of about0.01mm for both main and detector slits). The stabilizing circuits were inserted in the power sources of both the electro-static analyzer and the magnetic one, and the emission stabilizer in the ion source circuit. As the result, the drift of ion beam is reduced to a few parts in 107 per minute, and the good reproducibility of the operation is obtained. Under such operating conditions, the measurements of(C2H4-CO), (C2H4-N2)and(N2-CO)doublet mass differences were performed with the visual orthodox peak matching method. by changing the measuring procedures which may be the causes of systematic errors. On the way of the measurements, a considerable large systematic error was found. This error came from the exciting current of the switching relay coil used for the peak matching. The estimations of the magnitudes of expected systematic errors were done. Moreover, using the closure error of the triplet derived from the mass differences of the above mentioned doublets, the correction factor for the measured values was calculated, and the mass differences corrected by this factor are adopted as the most reliable values. Finally, the doublet mass difference of(C2H4-C2D2) was measured.