Methods of surface ionization for the measurement of chlorine’s isotopic composition

Jedinjenja hlorata i perhlorata koja se koriste kao herbicidi, pogonska čvrsta goriva i eksplozivi, i sve češće se prepoznaju kao zagađivači podzemnih voda [1]. Perhlorati su posebno opasni jer ometaju proizvodnju hormona u štitnoj žlezdi. Hlor je podložan izotopskom frakcionisanju fizičkim i hemijskim procesima. Varijacije u atomskim masama, kao i u zastupljenosti izotopa hlora su posledica njegovog izotopskog frakcionisanja tokom fizičkih, hemijskih i bioloških procesa. Upravo, te varijacije su korisne za određivanje porekla supstance i proučavanje ekoloških, hidroloških i geoloških procesa. Takođe, analizom izotopa hlora može se utvrditi i priroda zagađivača životne sredine odnosno da li je njegovo poreklo antropogeno ili ne. Informacije mogu biti važne iz pravnih razloga i za remedijaciju kontaminiranog područja [2, 3]. Hlor se u prirodi javlja u obliku dva stabilna izotopa 35Cl i 37Cl (relativnih atomskih masa, respektivno 34,968 8527 i 36,965 9026), čiji relativni izotopski sastav je 0,7553 i 0,2547 [4]. Merenje odnosa stabilnih izotopa hlora (n(37Cl)/n(35Cl)), kao i molske frakcije 36Cl (n(36Cl)/n(Cl)) pruža korisne informacije o poreklu hlorata i perhlorata u okruženju [2, 3]. Ranija merenja promene odnosa stabilnih izotopa hlora rađena su pomoću magnetnog masenog spektrometra sa površinskom jonizacijom u negativnom modu direktnim praćenjem jona Cl- [5], ili određivanjem promena izotopskog sastava praćenjem jona jedinjenja CH3 Cl+ [6]. Danas se metodom površinske jonizacije radi ispitivanja izotopskog sastava ne prate direktno joni hlora, već jedinjenja kao što su „superalkalni” klasteri tipa M2 Cl+ (M-alkalni metali). Razlog je, vrlo niska energija jonizacije pomenutih klastera (u nekim slučajevima niža od energije jonizacije cezijuma) što omogućava njihovu vrlo jednostavnu detekciju u masenom spektru [7]. Iako je ova metoda precizna i pouzdana, vrlo je skupa. Broj analiza izotopa hlora pomoću ugljovodonika koji u sastavu imaju hlor kao što je trihloretilen je u porastu, jer su ove vrste važni zagađivači životne sredine. Analiza kontinuiranog protoka trihloretilena molekula, bilo gasnom hromatografijom/izotopskom masenom spektrometrijom (GC/IRMS) ili sa masenom spektrometrijom GC/kvadrupol (GC/qMS), je inovativno analitičko rešenje, ali uprkos ranijim implementacijama, nedostaje joj rutinska aplikacija [8]. Pored navedenih tehnika u površinske metode jonizacije spada i masenospektrometrijska metoda laserske desorpcije i jonizacije (LDI). Preliminarni rezultati ukazuju da se „superalkalni“ klasteri tipa M2 Cl+ mogu detektovati navedenom metodom. S obzirom na jednostavnost korišćenja i njenu ekonomsku isplatljivost, analiza i ispitivanje promene izotopskog sastava pomoću LDI metode može predstavljati važan korak u analitic

Theoretical and experimental evaluation of K2Br+ and K3Br+ clusters' ionization energies

In current study, a non-stoichiometric bromine-doped potassium K2Br+and K3Br+clusters are generated by combining a Knudsen effusion cell as a chemical reactor with thermal or surface ionization,and selected by a magnetic sector mass spectrometer. Furthermore, their ionization energies (IEs) are calculated for the first time using B3LYP/9-ve PP(K),cc-pVTZ-PP(Br) level of theory. Herein, presented results indicate that experimentally obtained IEs by Ionov equation, 4.10 ± 0.20 eV for K2Br+, and 4.03 ± 0.20 eV for K3Br+, are in consistence with their theoretically determined IEs.Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 2016

Carbon dioxide activation of the plane tree seeds derived bio-char: Kinetic properties and application

Goal of this work is to establish technical feasibility and fundamentals of producing activated carbon from plane tree seeds biomass for porous materials derivation. Bio-chars produced via carbonization from plane tree seeds precursor were activated in CO2 at 750 and 850?C, during various residence times. Their surface area and porosity were characterized by N2 adsorption at 77 K. Surface areas of activated carbons can be correlated with kinetics mechanism and activation energy magnitudes of oxidation reaction by CO2, which are closely related to applied activation temperature. Result showed that high temperature activated carbon had higher gas adsorption as compared to activated carbon obtained from lower temperature during two-hour residence time. Breakthrough behavior was detected at 850?C where surface reactions dominate, and it is characterized by autocatalytic kinetic model under designed conditions. Both, temperature and CO2 concentration in vicinity of solid surface effect on breakthrough time of adsorbent. Derived bio-chars are converted into high quality activated carbons, with surface area of 776.55 m2/g, where micro-pores with pore diameters less than 2 nm prevail. Produced activated carbons have properties comparable with commercially available activated carbons, which can be successfully used for removal of harmful gaseous pollutants toward air purification

Generation of Au2Cl2n+1 (n = 1-3) cluster ions by laser desorption/ionization mass spectrometry

Gold chloride clusters were generated from an aqueous solution of gold-hydrochloric acid deposited onto the target plate using laser desorption/ionization (LDI) on a commercial matrix assisted laser desorption/ionization –time of flight (MALDI-TOF) mass spectrometric instrument. In our experimental conditions negative mode of LDI mass spectra provided the most valuable informations. The mass peaks at m/z about 339, 499, 571, 641, were assigned to AuCl4-, Au2Cl3-, Au2Cl5-, Au2Cl7-cluster ions, respectively. The Au2Cl5-and Au2Cl7-clusters are detected for the first time in this work. This research showed that LDI MS, thanks to its easy experimental procedure, a soft ionization technique which may be a useful characterization tool in the chemistry of heterogeneous gold clusters.Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 2016

Determination of corrosion products of Ag-Cu alloy by laser desorption ionization mass spectrometry

Silver alloys are generally used in the different fields of industry, including chemical processing, construction, heat exchangers, etc. Although Ag-Cu-Zn-Cd type of alloys, were widely exploited in the second half of the 20th century for their excellent properties, its use is forbidden in the EU due to the high toxicity of cadmium vapors. Ag-Cu-In type of alloy is a good alternative to Ag-Cu-Zn-Cd alloys, with great properties and can be used in various fields of industry. Most common methods for characterization of surface corrosion films of Ag-Cu alloys are: X-ray diffraction (XRD), scanning electron microscopy with energy dispersion spectroscopy (SEM-EDS), Raman spectroscopy and atomic force microscopy (AFM). Our current study focuses on the application of laser desorption ionization mass spectrometry (LDI MS) for determination of corrosion products of Ag-Cu alloy. The aim of this study was to confirm LDI MS as a fast, accurate and reliable method for determination of corrosion products on the surface of Ag-Cu-In alloy.IX Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 20-21, 2021; Belgrad

Preparation of Active Carbon Material By Activation With Various Hydroxide And Characterization Of Their Properties

The aim of this research is to obtain active carbon material from the plane tree fruit. The precursor was first treated with hydrothermal synthesis and then mechanochemically activated with various hydroxides and finally carbonization was done to promote activation.It can be concluded that by acting of different hydroxides (NaOH, BaOH, LiOH, KOH) in the same mass ratio and using the same precursor and the same process, totally different materials with different structure and morphology are obtained.The initial composition of the precursor as well as the final product (active carbon materials) were analyzed using a proximative and ultimate method. The active area surface, volume and pore size was determined using the BET method. Verification of surface-active reaction groups in the identified structures was carried out through Fourier-transform infrared (FTIR) spectroscopy. Morphology of resulting activated carbon materials has been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The application of the obtained materials is reflected in the fact that we removed the waste, we prevented the pollution of nature, and on the other hand we have obtained material that can be used for various purposes, for example, air and water filters, heating briquettes, fertilizer for plants, superconductors, etc.IX Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 20-21, 2021; Belgrad

Prospective of the LDI MS to characterization the corrosion products of silver-copper alloys on an example of the Ag-Cu-X (X- Zn, Pd, In) system

This work presents the perspective of applying the laser desorption/ionization mass spectrometry (LDI MS) for characterization the anode film of the Ag60Cu26Zn14, Ag58.5Cu31.5Pd10, and Ag63Cu27In10 alloys (at high concentrations of chloride ions in solutions). The reference LDI mass spectra of anode films of pure Ag and Cu have been used for the identification of product corrosion. Knowing the clusters detected in the reference spectra lead to the facilitating identification of the LDI mass spectrum of the sample and reduces the analysis time. The LDI MS analysis of these alloys revealed that the predominant corrosion product are AgCl (from AgnCln+1−/+, n = 1–3), and CuCl (from “superhalogen” CumCln− clusters, m = 1–2, n = 2–6); it also revealed Cu2(OH)3Cl (from Cu2(OH)(H2O)2+) and Cu2O (from Cu(H2O)+, Cu2O doped with chlorine). These results are in accordance with the X-ray diffraction and Raman analysis. The LDI MS spectra of alloys contain the additional peaks formed due to the mutual influences of different metals in the alloys (AgCuCl3− (AgCl-CuCl2−), AgCu2Cl4− (AgCl-CuCl-CuCl2−), and Ag2CuCl4− (AgCl-AgCl-CuCl−), which is consistent with the identified corrosion products. It should be noted that the LDI MS suggest the presence of CuCl2, which can be interpreted as the corrosion products retained in the porous films of alloys, and not detected by the other methods due to a small amount. The future theoretical and experimental studies of metal clusters, significant for metallurgy, can contribute that the LDI MS is becoming a powerful analytical tool for characterization the metal surfaces

Synthesis, characterization and properties of potassium halide clusters.

Masena spektrometrija sa Knudsen-ovom ćelijom (eng. Knudsen cell mass spectrometry, KCMS, odnosno masena spektrometrija sa efuzionom ćelijom ili masena spektrometrija molekulskog snopa) je metoda kojom se proučavaju osobine neorganskih supstanci, poput metala i njihovih legura (posebno oksida, sulfida, selenida, telurida i halogenida). Ova metoda koristi se i za dobijanje, analizu i karakterizaciju klastera, grupe konstituenata (atoma, molekula) međusobno povezanih vezama različite jačine. KCMS-om mogu se dobiti i informacije o kvalitativnom sastavu gasovite faze odnosno o identitetu molekula koji nastaju u hemijskim reakcijama pod neravnotežnim uslovima, kao i uticaju vremena, temperature i gustine fluksa upadnih čestica na brzinu stvaranja novih molekula, parcijanom pritisku svih pojedinačnih gasovitih komponenti, promenama parcijalnog pritiska sa temperaturom, kao i kinetici procesa isparavanja. Takođe, koristi se i za izračunavanje parcijalnih pritisaka pojedinačnih komponenti u zasićenoj pari korišćenjem jednačina koje povezuju jonske intenzitete i parcijalne pritiske, povezivanjem eksperimentalno određenih veličina, inteziteta jona i temperature u ćeliji sa pritiskom zasićene pare ispitivane supstance. Postojanje klastera kalijum-halogenida (KnX, X = F, Cl, Br, I) je teorijski opisano, mada do sada nisu eksperimentalno dobijeni usled velikog rasipanja jona, šuma i gubitka određene količine neutrala koji nastaju u samoj klasičnoj Knudsen-ovoj efuzionoj ćeliji, što, između ostalog, otežava identifikaciju spektra. Stoga je, u okviru ove doktorske disertacije, predloženo novo konstrukciono rešenje za primenu Knudsen-ove efuzione ćelije koje se odnosi na promenu položaja ćelije u odnosu na jonsku komoru, kao i drugačiju tehniku jonizacije – tehnika površinske ili termalne jonizacije, čime je omogućena sinteza, karakterizacija i određivanje svojstava KnX klastera. Naime, konstruisanje, na ovaj način, stabilnog izvora jona klastera, rezultiralo je u direktnom stvaranju jona, detektovanju klastera niskih jonskih prinosa, kao i karakterizaciji i određivanju svojstava određenih vrsta klastera. Upravo, koristeći klastere definisane veličine i sastava, kao elementarne komponente, omogućilo je stvaranje nereaktivnih stabilnih materijala sa unapred definisanim osobinama.Knudsen cell mass spectrometry, KCMS, or mass spectrometry with effusion cell or molecular beam mass spectrometry, is a method for investigating properties of inorganic substances such as metals and their alloys (in particular oxide, sulfide, selenide, telluride and halogenide). This method is also used for the synthesis, analysis and characterization of clusters, groups of constituents (atoms, molecules) connected with bounds of different strength. Furthemore, it provides the information about the vapor phase qualitative composition or identity of the molecules that are formed in chemical reactions under equilibrium conditions, as well as the effects of time, temperature and incident particles flux density on generating speed of new molecules, partial pressure of individual gaseous components, changes in partial pressure with temperature, as well as the kinetics of the process of evaporation. It is also applied to calculate the partial pressures of the individual components in the saturated steam using equations that connect ion intensities and partial pressures, connecting experimentally determined size, intensity and temperature of ions in the cell with the saturated vapor pressure of tested substance. The existence of potassium halide clusters (KnX, X = F, Cl, Br, I) is theoretically described, although, till now, they have not been experimentally obtained due to the large ion spreading, noise, and loss of a certain amount of neutrals generated by common Knudsen effusion cell, which, among the other things, makes the identification of the spectrum difficult. Therefore, this doctoral dissertation, proposed a new structural solution for Knudsen's effusion cell implementation that resulted in changing the position of the cell in relation to the ion chamber, as well as the use of different ionization technique, the technique of surface or thermal ionization, enabling to synthesize, characterize and determine properties of KnX clusters. This modification provided, through the construction of a stable source of ion clusters, a direct ion generation, detection of clusters with low yields, as well as determination of the properties of certain types of clusters. Particularly, synthesis of clusters with predefined size, composition and thus, properties provides the opportunity to create new, non-reactive, stable materials

Synthesis, characterization and properties of potassium halide clusters.

Masena spektrometrija sa Knudsen-ovom ćelijom (eng. Knudsen cell mass spectrometry, KCMS, odnosno masena spektrometrija sa efuzionom ćelijom ili masena spektrometrija molekulskog snopa) je metoda kojom se proučavaju osobine neorganskih supstanci, poput metala i njihovih legura (posebno oksida, sulfida, selenida, telurida i halogenida). Ova metoda koristi se i za dobijanje, analizu i karakterizaciju klastera, grupe konstituenata (atoma, molekula) međusobno povezanih vezama različite jačine. KCMS-om mogu se dobiti i informacije o kvalitativnom sastavu gasovite faze odnosno o identitetu molekula koji nastaju u hemijskim reakcijama pod neravnotežnim uslovima, kao i uticaju vremena, temperature i gustine fluksa upadnih čestica na brzinu stvaranja novih molekula, parcijanom pritisku svih pojedinačnih gasovitih komponenti, promenama parcijalnog pritiska sa temperaturom, kao i kinetici procesa isparavanja. Takođe, koristi se i za izračunavanje parcijalnih pritisaka pojedinačnih komponenti u zasićenoj pari korišćenjem jednačina koje povezuju jonske intenzitete i parcijalne pritiske, povezivanjem eksperimentalno određenih veličina, inteziteta jona i temperature u ćeliji sa pritiskom zasićene pare ispitivane supstance. Postojanje klastera kalijum-halogenida (KnX, X = F, Cl, Br, I) je teorijski opisano, mada do sada nisu eksperimentalno dobijeni usled velikog rasipanja jona, šuma i gubitka određene količine neutrala koji nastaju u samoj klasičnoj Knudsen-ovoj efuzionoj ćeliji, što, između ostalog, otežava identifikaciju spektra. Stoga je, u okviru ove doktorske disertacije, predloženo novo konstrukciono rešenje za primenu Knudsen-ove efuzione ćelije koje se odnosi na promenu položaja ćelije u odnosu na jonsku komoru, kao i drugačiju tehniku jonizacije – tehnika površinske ili termalne jonizacije, čime je omogućena sinteza, karakterizacija i određivanje svojstava KnX klastera. Naime, konstruisanje, na ovaj način, stabilnog izvora jona klastera, rezultiralo je u direktnom stvaranju jona, detektovanju klastera niskih jonskih prinosa, kao i karakterizaciji i određivanju svojstava određenih vrsta klastera. Upravo, koristeći klastere definisane veličine i sastava, kao elementarne komponente, omogućilo je stvaranje nereaktivnih stabilnih materijala sa unapred definisanim osobinama.Knudsen cell mass spectrometry, KCMS, or mass spectrometry with effusion cell or molecular beam mass spectrometry, is a method for investigating properties of inorganic substances such as metals and their alloys (in particular oxide, sulfide, selenide, telluride and halogenide). This method is also used for the synthesis, analysis and characterization of clusters, groups of constituents (atoms, molecules) connected with bounds of different strength. Furthemore, it provides the information about the vapor phase qualitative composition or identity of the molecules that are formed in chemical reactions under equilibrium conditions, as well as the effects of time, temperature and incident particles flux density on generating speed of new molecules, partial pressure of individual gaseous components, changes in partial pressure with temperature, as well as the kinetics of the process of evaporation. It is also applied to calculate the partial pressures of the individual components in the saturated steam using equations that connect ion intensities and partial pressures, connecting experimentally determined size, intensity and temperature of ions in the cell with the saturated vapor pressure of tested substance. The existence of potassium halide clusters (KnX, X = F, Cl, Br, I) is theoretically described, although, till now, they have not been experimentally obtained due to the large ion spreading, noise, and loss of a certain amount of neutrals generated by common Knudsen effusion cell, which, among the other things, makes the identification of the spectrum difficult. Therefore, this doctoral dissertation, proposed a new structural solution for Knudsen's effusion cell implementation that resulted in changing the position of the cell in relation to the ion chamber, as well as the use of different ionization technique, the technique of surface or thermal ionization, enabling to synthesize, characterize and determine properties of KnX clusters. This modification provided, through the construction of a stable source of ion clusters, a direct ion generation, detection of clusters with low yields, as well as determination of the properties of certain types of clusters. Particularly, synthesis of clusters with predefined size, composition and thus, properties provides the opportunity to create new, non-reactive, stable materials

Production of Heterogeneous Superalkali Clusters Linf (N=2-6) By Knudsen - Cell Mass Spectrometry

The superalkali clusters are important because they can be considered as potential building block for the assembly of novel nanostructured materials with unique structural, electronic, optical, magnetic, and thermodynamic properties. We have modified and used the Knudsen cell mass spectrometer in order to obtain and measurement of the ionization potentials of the superalkali clusters. In this work the clusters LinF (n = 2 - 6) have produces in the vapor over a mixture of lithium fluoride and lithium iodide by means of Knudsen cell which is placed into ionization chamber of the magnetic sector mass spectrometer. The simultaneous production and mass spectrometric detection of the ionic of clusters provide information on the conditions of formation and the distribution of these ion species. It is observed that the ions of clusters with an even numbered of lithium atoms are more stable than the ions of clusters with an odd numbered of lithium atoms. The clusters Li5F and Li6F were detected experimentally for the first time with their ionization energies of (4.29 +/- 0.25) eV, and (4.24 +/- 0.25) eV, respectively