The mass spectrometric characteristics of phorate and two phosphorothioates are discussed and the chief fragments and fragmentation mechanism are identified with the interpretation of mass spectrum.

(1) the respective fragments m/z 176, 191, 192, 193, 161 are formed from molecular ion M~+ on the fragmentation mechanism via various cleavage modes; (2)the base peak at m/z 191 is formed with the loss of a neutral molecule via the ortho effect; (3) the base peak m/z 191 may further be cleaved to form fragments m/z 147, 132, 91; (4) the cleavage of C--N bond in si.

Results show that the atom N is most likely to dissociate in neutral fragment forms of NH2,HCN,HCN2,N3 and N4,while the fragmentation mechanisms are the cleavage of C—N and N—N and the rearrangment.

Influence of loading rate on critical event of cleavage fracture in notched specimen of low alloy steel;

Hard brittle particles can have an important influence on cleavage fracture in steels, and can act as cleavage initiators.

The results show that before a critical load is reached, the crack tip is blunted only and in its vicinity the three criteria of cleavage fracture are satisfied in different regions separated from each other.