Laser ablation synthesis of new gold phosphides using red phosphorus and nanogold as precursors. Laser desorption ionisation time-of-flight mass spectrometry

Gold phosphides show unique optical or semiconductor properties and there are extensive high technology applications, e.g. in laser diodes, etc. In spite of the various AuP structures known, the search for new materials is wide. Laser ablation synthesis is a promising screening and synthetic method. Generation of gold phosphides via laser ablation of red phosphorus and nanogold mixtures was studied using laser desorption ionisation time-of-flight mass spectrometry (LDI TOFMS). Gold clusters Au_m⁺ (m = 1 to ~35) were observed with a difference of one gold atom and their intensities were in decreasing order with respect to m. For P_n⁺(n = 2 to ~111) clusters, the intensities of odd-numbered phosphorus clusters are much higher than those for even-numbered phosphorus clusters. During ablation of P-nanogold mixtures, clusters Au_m⁺ (m = 1-12), P_n⁺ (n = 2-7, 9, 11, 13–33, 35–95 (odd numbers)), AuP_n⁺ (n = 1, 2–88 (even numbers)), Au₂P_n⁺ (n = 1-7, 14–16, 21–51 (odd numbers)), Au₃P_n⁺ (n = 1-6, 8, 9, 14), Au₄P_n⁺ (n = 1-9, 14–16), Au₅P_n⁺(n = 1-6, 14, 16), Au₆P_n⁺ (n = 1-6), Au₇P_n⁺ (n = 1-7), Au₈P_n⁺ (n = 1-6, 8), Au₉P_n⁺ (n = 1-10), Au₁₀P_n⁺ (n = 1-8, 15), Au₁₁P_n⁺ (n = 1-6), and Au₁₂P_n⁺ (n = 1, 2, 4) were detected in positive ion mode. In negative ion mode, Au_m^– (m = 1–5), P_n^– (n = 2, 3, 5–11, 13–19, 21–35, 39, 41, 47, 49, 55 (odd numbers)), AuP_n^– (n = 4–6, 8–26, 30–36 (even numbers), 48), Au₂P_n^– (n = 2–5, 8, 11, 13, 15, 17), Au₃P_n^– (n = 6–11, 32), Au₄P_n^– (n = 1, 2, 4, 6, 10), Au₆P₅^–, and Au₇P₈^– clusters were observed. In both modes, phosphorus-rich Au_mP_n clusters prevailed. The first experimental evidence for formation of AuP₆₀ and gold-covered phosphorus Au₁₂P_n (n = 1, 2, 4) clusters is given. The new gold phosphides generated might inspire synthesis of new Au-P materials with specific properties. Copyright © 2012 John Wiley & Sons, Ltd.