Laser ablation synthesis of arsenic-phosphide Asm Pn clusters from As-P mixtures. Laser desorption ionisation with quadrupole ion trap time-of-flight mass spectrometry: The mass spectrometer as a synthesizer.

RATIONALE: Only a few arsenic phosphides are known. A high potential for the generation of new compounds is offered by Laser Ablation Synthesis (LAS) and when Laser Desorption Ionization (LDI) is coupled with simultaneous Time-Of-Flight Mass Spectrometry (TOFMS), immediate identification of the clusters can be achieved. METHODS: LAS was used for the generation of arsenic phosphides via laser ablation of phosphorus-arsenic mixtures while quadrupole ion trap time-of-flight mass spectrometry (QIT-TOFMS) was used to acquire the mass spectra. RESULTS: Many new Asm Pn± clusters (479 binary and 369 mono-elemental) not yet described in the literature were generated in the gas phase and their stoichiometry determined. The likely structures for some of the observed clusters arbitrary selected (20) were computed by density functional theory (DFT) optimization. CONCLUSIONS: LAS is an advantageous approach for the generation of new Asm Pn clusters, while mass spectrometry was found to be an efficient technique for the determination of cluster stoichiometry. The results achieved might inspire the synthesis of new materials.

Laser Desorption Ionization of As2Ch3 (Ch = S, Se, and Te) Chalcogenides Using Quadrupole Ion Trap Time-of-Flight Mass Spectrometry: A Comparative Study.

Laser desorption ionization using time-of-flight mass spectrometer afforded with quadrupole ion trap was used to study As2Ch3 (Ch = S, Se, and Te) bulk chalcogenide materials. The main goal of the study is the identification of species present in the plasma originating from the interaction of laser pulses with solid state material. The generated clusters in both positive and negative ion mode are identified as 10 unary (S p+/- and As m+/- ) and 34 binary (As m S p+/- ) species for As2S3 glass, 2 unary (Se q+/- ) and 26 binary (As m Se q+/- ) species for As2Se3 glass, 7 unary (Te r+/- ) and 23 binary (As m Te r+/- ) species for As2Te3 material. The fragmentation of chalcogenide materials was diminished using some polymers and in this way 45 new, higher mass clusters have been detected. This novel approach opens a new possibility for laser desorption ionization mass spectrometry analysis of chalcogenides as well as other materials. Graphical abstract ᅟ.

Laser Ablation Synthesis of Gold Selenides by using a Mass Spectrometer as a Synthesizer: Laser Desorption Ionization Time-of-Flight Mass Spectrometry.

Methods for the rapid construction of new chemical motifs have the potential to accelerate the development of nanoscience. The synthesis of new chemical entities by laser ablation has been systematically demonstrated by using mixtures of gold and selenium. The compounds generated are detected by time-of-flight mass spectrometry and, for selected compounds, the structure is investigated by using density functional theory optimization. In total, 67 new gold selenide clusters have been synthesized, demonstrating an unsuspected richness in gold chemistry. Chemical species generated in the gas phase might inspire new routes for the synthesis of novel compounds in the solid state.

Novel electrospun gelatin/oxycellulose nanofibers as a suitable platform for lung disease modeling.

Novel hydrolytically stable gelatin nanofibers modified with sodium or calcium salt of oxycellulose were prepared by electrospinning method. The unique inhibitory effect of these nanofibers against Escherichia coli bacteria was examined by luminometric method. Biocompatibility of these gelatin/oxycellulose nanofibers with eukaryotic cells was tested using human lung adenocarcinoma cell line NCI-H441. Cells firmly adhered to nanofiber surface, as determined by scanning electron microscopy, and no signs of cell dying were detected by fluorescent live/dead assay. We propose that the newly developed gelatin/oxycellulose nanofibers could be used as promising scaffold for lung disease modeling and anti-cancer drug testing.

Structural elucidation of AgAsS2 glass by the analysis of clusters formed during laser desorption ionisation applying quadrupole ion trap time-of-flight mass spectrometry.

RATIONALE: The structure of AgA(s)S2 glass, which has a broad range of applications, is still not well understood and a systematic mass spectrometric analysis of AgA(s)S2 glass is currently not available. Elucidation of the structure should help in the development of this material. METHODS: The AgA(s)S2 glass was prepared by the melt-quenched technique. Laser desorption ionisation (LDI) using quadrupole ion trap time-of-flight mass spectrometry (QIT-TOFMS) was used to follow the generation of Ag(m)As(n)S(x) clusters. The stoichiometry of the clusters generated was determined via collision-induced dissociation (CID) and modelling of isotopic patterns. The AgA(s)S2 glass was characterised by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. RESULTS: The LDI of AgA(s)S2 glass leads to the formation of unary (Ag+/− and As(3+)) species, 38 binary (As(n)S(x), Ag(m)S(x)), and 98 ternary (Ag(m)As(n)S(x)) singly charged clusters. The formation of silver-rich nano-grains during AgA(s)S2 glass synthesis has been identified using TEM analysis and also verified by QIT-TOFMS. CONCLUSIONS: TOFMS was shown to be a useful technique to study the generation of Ag(m)As(n)S(x )clusters. SEM, TEM and EDX analysis proved that the structure of AgA(s)S2 glass is 'grain-like' where grains are either: (1) Silver-rich 'islands' (Ag(m,) m up to 39) connected by arsenic and/or sulfur or arsenic sulfide chains or (2) silver sulfide (Ag2S)m (m = 9-20) clusters also similarly inter-connected. This obtained structural information may be useful for the development of ultra-high-density phase-change storage and memory devices using this kind of glass as a base.

Laser ablation generation of clusters from As-Te mixtures, As-Te glass nano-layers and from Au-As-Te nano-composites. Quadrupole ion trap time-of-flight mass spectrometry.

RATIONALE: Arsenic tellurides have found important applications in various fields of science, but only a few gold-arsenic tellurides have been reported. Laser ablation synthesis (LAS), a suitable method for the generation of new compounds, has been used to generate clusters from As-Te mixtures, an As-Te glass and Au-As-Te nano-composites. METHODS: Chalcogenide glass nano-layers prepared via Physical Vapour Deposition - thermal evaporation were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). LAS with laser desorption ionisation quadrupole ion trap time-of-flight mass spectrometry (LDI QIT TOFMS) was used for the generation and analysis of new AuxAsmTen clusters. The stoichiometry of the clusters was determined via isotopic envelope modelling. RESULTS: A simple procedure for the preparation of the Au-As-Te nano-composite was developed. From As-Te mixtures only five binary AsmTen clusters were generated, while from a glass layer 10 binary AsmTen clusters were identified, because during the deposition of the glass the elements reacted with each other to form a complex three-dimensional (3D) structure. Using LAS on the Au-As-Te nano-composite leads to the formation of six unary Ten (n = 1-6), 16 binary (AsmTen and AuxTen), and 31 ternary AuxAsmTen clusters. CONCLUSIONS: LAS was demonstrated to be a useful technique for the generation of AuxAsmTen clusters in the gas phase. More AsmTen clusters were generated from the deposited glass layers than from As-Te mixtures. Most of the ternary AuxAsmTen clusters generated from the nano-composite are reported here for the first time.

Generation of new Agm Ten clusters via laser ablation synthesis using Ag-Te nano-composite as precursor. Quadrupole ion trap time-of-flight mass spectrometry.

RATIONALE: Silver tellurides find applications in the development of infrared detection, imaging, magnetics, sensors, memory devices, and optic materials. However, only a limited number of silver tellurides have been described to date. Laser ablation synthesis (LAS) was selected to generate new Ag-Te clusters. METHODS: Isothermal adsorption was used to study the formation of silver nano-particles-tellurium aggregates. Laser desorption ionization quadrupole ion trap time-of-flight mass spectrometry (LDI-QIT-TOFMS) was used for the generation and analysis of Agm Ten clusters. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to visualize the structure of materials. The stoichiometry of the generated clusters was determined by computer modeling of isotopic patterns. RESULTS: A simple, one-pot method for the preparation of Ag-Te nano-composite was developed and found suitable for LAS of silver tellurides. The LDI of Ag-Te nano-composite leads to the formation of 11 unary and 52 binary clusters. The stoichiometry of the 34 novel Agm Ten clusters is reported here for the first time. CONCLUSIONS: LAS with TOFMS detection was proven to be a powerful technique for the generation of silver telluride clusters. Knowledge of the stoichiometry of the generated clusters might facilitate the further development of novel high-tech silver tellurium nano-materials.

Generation of Au(p)Ag(q)Te(r) clusters via laser ablation synthesis using Au-Ag-Te nano-composite as precursor: quadrupole ion-trap time-of-flight mass spectrometry.

RATIONALE: Metal tellurides have applications in various fields of science and technology but only a few gold-silver tellurides have been reported. The laser ablation synthesis (LAS) method allows the preparation of nano-materials from solid substrates. Therefore, this method was selected to synthesise some gold-silver tellurides. METHODS: Laser desorption ionisation quadrupole ion trap time-of-flight mass spectrometry (LDI QIT TOF MS) was used for the generation of new Au(p)Ag(q)Te(r) clusters. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to characterise the materials. The stoichiometry of the clusters generated was determined via collision-induced dissociation (CID) and modeling of isotopic patterns. RESULTS: Chemisorption of gold and silver nano-particles on tellurium powder led to the formation of a new kind of Au-Ag-Te nano-composite. The LDI of this nano-composite yielded nine unary (Ag(q), Te(r)), 40 binary (Au(p)Te(r) and Ag(p)Te(r)) and 78 ternary clusters. The stoichiometry of these novel Au(p)Ag(q)Te(r) clusters is reported here for the first time. CONCLUSIONS: The new Au-Ag-Te nano-composite was found to be a more suitable precursor for the generation of clusters than the mixtures of the elements. TOF MS was shown to be a useful technique for following the generation of gold-silver tellurides. Knowledge of the cluster stoichiometry could accelerate the further development of novel high-tech materials such as chalcogenide glasses.

Laser ablation synthesis of new gold arsenides using nano-gold and arsenic as precursors. Laser desorption ionisation time-of-flight mass spectrometry and spectrophotometry.

RATIONALE: Currently, a limited number of gold arsenides have been described, some of which have important industrial applications, Laser ablation synthesis (LAS) has been employed in an attempt to generate some novel gold arsenide compounds. METHODS: LAS of gold arsenides was performed using nano-gold (NG) and arsenic as precursors. The clusters formed during laser desorption ionisation (LDI) were analysed by mass spectrometry using a quadrupole ion trap and reflectron time-of-flight analyser to determine the stoichiometry. UV/VIS spectrophotometry was used to follow possible hydrothermal synthesis of gold arsenides. RESULTS: LAS of NG yielded singly charged gold clusters Aum (+(-)) (m = 1-35). LAS of bulk arsenic and nano-arsenic produced Asn (+(-)) clusters with n = 2-10 and n = 2-20, respectively. Laser ablation of Au-As nano-composites or NG-As mixtures generated Aum (+(-)) (m = 1-12), Asn (+(-)) (n = 3-4), and several series of Aum Asn (+(-)) (m = 1-60, n = 1-18) clusters. Over 450 species of gold arsenide clusters and 212 mixed chlorinated Aum Asn Clx clusters were detected and their stoichiometry determined. CONCLUSIONS: Many new gold arsenides were synthesised via LAS for the first time with Au-As composites and NG-As mixtures of different Au:As ratios using mass spectrometry to determine cluster stoichiometry. The resolved stoichiometry of Aum Asn clusters determined in this study could accelerate the development of advanced Au-As nano-materials.

Laser ablation synthesis of new phosphorus nitride clusters from α-P3N5 via Laser Desorption Ionization and Matrix Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry.

Phosphorus nitride clusters generated during Laser Desorption Ionization (LDI) and Matrix-Assisted Laser Desorption Ionization (MALDI) of solid P(3) N(5) were analyzed via Time-of-Flight Mass Spectrometry (TOF MS). The LDI TOF mass spectra show the formation of series of clusters: P(m)N(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 P(m)N(n)(-) (m=4,5; n=1). Using 3-hydroxypicolinic acid (HPA) as a matrix the P(m)N(n)(+) species (m=1-4, 6, 8) with a high nitrogen content (n=4, 5, 8, 10-12, 20) were identified. The formation of a N(6)(-) cluster was also detected using a C(60) matrix. Under various conditions singly charged P(m)(+) (m=2-7, 9, 13), P(m)(-) (m=3-11, 13, 15, 17), N(n)(+) (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 N(15)(-)) generated by laser desorption from a solid material are described for the first time. The stoichiometry of the P(m)N(n) clusters was determined via isotopic envelope analysis and computer modelling. The composition of the clusters with respect to the crystalline structure of α-P(3)N(5) is discussed.

Laser ablation synthesis of phosphorus sulphides, selenides and ternary Pp Sq Ser clusters from various precursors.

Laser ablation (LA) synthesis with simultaneous time-of-flight mass spectrometric (TOF MS) analysis was used to examine the formation and composition of ternary Pp Sq Ser clusters. Clusters formed by LA of various precursors are singular, binary and ternary. Formation of negative or positive singly charged Pp, Sq and Ser clusters, where Pp + (p = 1-249), Pp* (p = 1-191), Sq* (q = 1-15), Sq + (q = 1-12), Ser* (r = 1-8) and Ser+ (r = 1-9), was identified. High numbers of binary Pp Sq, Sq Ser (35) or ternary Pp Sq Ser (138) clusters were formed by LA synthesis from the various mixtures. Most of the ternary Pp Sq Ser clusters were formed either from a mixture of P4S3 with selenium (grey) or from a mixture of SeS2 with red phosphorus. In total, 138 new ternary Pp Sq Ser clusters were identified. The conditions for the formation of such possible prospective nano-materials are given.

Laser desorption/ionization and laser ablation synthesis of new selenium oxide compounds from selenium(IV) dioxide.

Laser desorption/ionization (LDI) and/or laser ablation (LA) of selenium dioxide crystals or its mixtures with sodium peroxide were studied using a commercial matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometer. It was found that LDI and LA of selenium (IV) dioxide not only ionizes SeO(2), but also leads to the formation of several positively and negatively singly charged species: SeO(n) (+) (n = 0-2), Se(2) (+), SeO(n) (-) (n = 0-4), Se(2)O(n) (-) (n = 3-7), Se(3)O(n) (-) (n = 4-9), Se(4)O(n) (-) (n = 8-10). A rather high yield of selenium species in the positive ion mode, Se(m) (+) (m = 1-8) and Se(m)OH(+) (m = 3-7), was obtained by using the MALDI approach while the species detected in the negative ion mode, SeO(n) (-) (n = 0-4), Se(2)O(n) (-) (n = 3-7), Se(3)O(n) (-) (n = 4-9), and Se(4)O(n) (-) (n = 9, 10), were the same as those observed during LDI/LA of selenium dioxide. The addition of sodium peroxide to selenium dioxide with the aim of enhancing its oxidation and thus increasing the production of SeO(4) product resulted in extensive cationization of the species with sodium or potassium. The following positively and negatively charged species were identified: Se(+), Se(2) (+), Se(2)OH(+), Se(2)ONa(+), SeO(n) (-) (n = 0-3), and Se(2)O(n) (-) (n = 0, 1, 4). Also observed in mass spectra of such mixtures, various mixed sodium and/or potassium adducts with selenium oxide species, e.g. Se(2)O(4)K(2)Na(-), were identified. In all, 26 totally new species, Se(2)O(n) (-) (n = 3-6), Se(3)O(n) (-) (n = 4-9), Se(4)O(n) (-) (n = 8-10), Se(4)O(11)H(5) (-), Se(4)O(12)H(3) (-), Se(2)O(4)Na(-), Se(2)O(5)HNa(-), Se(2)O(5)HNa(2) (-), Se(3)O(6)K(2)Na(-), Se(3)O(6)K(2)Na(2) (-), Se(2)ONa(+), and Se(m)OH(+) (m = 3-7), were described for the first time. Also, for the first time, the formation of selenium(IV) diperoxide, O-O-Se-O-O or O(2)SeO(2), is described. The stoichiometries of the compounds generated were confirmed using isotopic pattern modeling.

Laser ablation synthesis of selenium superoxide anion SeO4- via selenium trioxide photolysis. Time-of-flight mass spectrometry and ab initio calculations.

Laser desorption/ionisation and laser ablation of solid selenium trioxide, as well as the gas-phase behaviour of selenium trioxide, were studied. Selenium trioxide undergoes photochemical decomposition and, from the mass spectra obtained by laser desorption/ionisation time-of-flight mass spectrometry (LDI-TOF-MS), the following species were identified: O-, O2-, O3-, SeO-, SeO2-, SeO3-, SeO4-, Se2O7-, Se3O11-, and Se4O14-. Formation of the selenium superoxide SeO4- anion is described in this work for the first time. In addition, low-abundance selenium species such as Se2O8H2-, Se3O11H-, and Se4O15H2- were also detected. The stoichiometry of all ions was confirmed via isotopic pattern modeling and/or post-source decay (PSD) analysis. Photolysis of selenium trioxide leads partly to ozone formation. It was found that the most likely mechanisms of selenium superoxide formation are oxidation of selenium trioxide with ozone and/or reactive oxygen radicals, or photolysis of selenium trioxide tetramer (SeO3)4. Therefore, ab initio calculations were performed to support the mass spectrometric evidence and to suggest probable geometries for selenium superoxide anion SeO4- and diselenium superoxide anion Se2O7-, as well as to provide insight into and/or predict possible formation pathways. It has been found that both cyclic and non-cyclic peroxide structures of SeO4- and Se2O7- ions are possible. In addition, the SeO4 structure was also calculated guided by thermodynamic considerations using Gaussian-2 methodology, and the inferred stability of the SeO4 neutral molecule was supported by ab initio calculations.

Laser ablation generation of cluster ions from concentrated sulfuric and selenic acids.

The generation and identification of novel homo- and hetero-polyacid clusters was achieved using a standard matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometer. The formation of several singly charged species was achieved via the interaction of a laser beam with concentrated sulfuric acid, selenic acid or their mixtures, applied on a graphite microcrucible. A higher yield of the species was observed in the negative detection mode, where sulfuric acid adducts HSO(4) (-) . mH(2)SO(4) (m = 0-3) and HSO(4) (-) . mH(2)SO(4) . SO(3) (m = 1, 2), and selenic acid adducts HSeO(4) (-), HSeO(4) (-) . X (X = SeO(3), H(2)SeO(4), 2SeO(3), H(2)SO(4) . SeO(3)) and NaSeO(4) (-). Y (Y = H(2)SeO(4), H(2)SeO(4). SeO(3), 2H(2)SO(4), H(2)SeO(4) . 2SeO(3), 2H(2)SeO(4) . SeO(3), 3H(2)SeO(4)), were identified. In the mass spectra of the mixture of acids, besides the homo-polyacidic adducts, eleven mixed species containing both sulfuric and selenic acid molecules or ions were identified, of which the heaviest was found to correspond to NaSeO(4) (-) . H(2)SeO(4) . 3SO(3). The stoichiometry of the species was confirmed using isotopic pattern modeling.

Analysis and calculation of the 31P and 19F NMR spectra of hexafluorocyclotriphosphazene.

The higher order high-resolution (31)P and (19)F NMR spectra of hexafluorocyclotriphosphazene (F(2)PN)(3) were measured at 183 K and interpreted using subspectral analysis and iterative fitting computation. (F(2)PN)(3) forms a rigid nine-spin system [A[X](2)](3) with D(3h) symmetry. Two complete and very similar sets of six experimental spin-spin coupling constants, (1)J(P,F), (2)J(P,P), (2)J(F,F), (3)J(P,F), (4)J(F,F)(cis) and (4)J(F,F)(trans), were determined for the first time. Theoretical DFT calculations of chemical shifts and coupling constants were performed to assess their predictive value. The PP/aug-cc-pVDZ treatment rendered the best agreement with experimental data.