The Atomic Mass Unit, the Avogadro Constant, and the Mole: A Way To Understanding

2011 ◽  
Vol 89 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Andrzej Barański
Keyword(s):  
Atomic Mass ◽  
Atomic Mass Unit ◽  
Mass Unit ◽  
Avogadro Constant

Photoionization and Photofragmentation of BxNy Clusters Produced by Photoablation of Boron Nitride Followed by Supersonic Expansion Cooling

1992 ◽  
Vol 285 ◽  
Author(s):  
Paul A. Roland ◽  
Sam J. La Placa ◽  
James J. Wynne
Keyword(s):  
Mass Spectrum ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Atomic Mass ◽  
Atomic Mass Unit ◽  
Experimental Conditions ◽  
Supersonic Expansion ◽  
Mass Unit ◽  
Expansion Cooling ◽  
532 Nm

ABSTRACTPhotoablation of isotopically pure boron metal and hexagonal boron nitride with a 532 nm laser, followed by supersonic expansion cooling, produces a variety of Bx, and BxNy, clusters, which are detected by photoionization of the neutral clusters with a 194 nm laser, followed by time-of-flight (TOF) mass spectrometry. Under certain experimental conditions, the mass spectrum derived from boron nitride shows resolved peaks corresponding to the clusters Bx+1Ny+. Under different experimental conditions, the mass spectrum shows an unresolved region corresponding to clusters ranging from atomic mass unit 100–1000 as well as resolved peaks, corresponding to Bx+ clusters for x = 2 − 100. These resolved peaks grow with increasing photoionization fluence, while the envelope of the unresolved region changes shape and grows with a diminished dependence on fluence. These data are interpreted as evidence that the unresolved clusters are being photofragmented as well as photoionizated by the 194 nm radiation, and the products of such photofragmentation are the aforementioned Bx+ clusters.

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