Laser ablation synthesis of new phosphorus nitride clusters from α-P_3N_5 via laser desorption ionization and matrix assisted laser desorption ionization time-of-flight mass spectrometry

摘要

Phosphorus nitride clusters generated during Laser Desorption Ionization (LDI) and Matrix-Assisted Laser Desorption Ionization (MALDI) of solid P _3N_5 were analyzed via Time-of-Flight Mass Spectrometry (TOF MS). The LDI TOF mass spectra show the formation of series of clusters: P_mN_n+ {(m = 1; n = 8-11), (m = 4; n = 3-4), (m = 5; n = 1-5), (m = 6; n = 1-3, 5-8), (m = 2-7; n = 1), (m = 5-10; n = 2), (m = 4-6; n = 3), (m = 4,5; n = 4), (m = 5,6; n = 5)}, and PmN n- (m = 4,5; n = 1). Using 3-hydroxypicolinic acid (HPA) as a matrix the PmNn+ species (m = 1-4, 6, 8) with a high nitrogen content (n = 4, 5, 8, 10-12, 20) were identified. The formation of a N6- cluster was also detected using a C60 matrix. Under various conditions singly charged P m+ (m = 2-7, 9, 13), Pm- (m = 3-11, 13, 15, 17), Nn+ (n = 5, 9, 10, 12, 13), and N n- (n = 6, 10-15) clusters were identified in the mass spectra. Such high nitrogen content clusters (up to N15-) generated by laser desorption from a solid material are described for the first time. The stoichiometry of the PmNn clusters was determined via isotopic envelope analysis and computer modelling. The composition of the clusters with respect to the crystalline structure of α-P3N5 is discussed.