Yeghis Keheyan

• Associated professor Chemistry
• voluntary researcher retired at University of Rome "La Sapienza

This study focuses on the archeological characterization of potsherds from Tigranakert in Artsakh belonging to different centuries (from 9–13 century) using SEM/EDS technique. Archeometry and archeological science correspond and refer to the application of scientific techniques to the analysis of archeological materials, as well as the processes in...

Archaeometry and archaeological science correspond and refer to the application of scientific techniques to the analysis of archaeological materials, as well as the processes involved in their manufacture [Williams 2005, Virgil de la Mencia 2008, Martinon-Torres 2015]1–3]. This paper presents study of a set of ceramic samples using stratigraphic an...

The well-known copper-molybdenum porphyry deposits of the Zangezur ore district are spatially associated with the uneven-aged intrusive rocks of the Meghri pluton. Less well known are studies on the distribution of rare earth elements in intrusive rocks. This article discusses the prospects for rare earth mineralization of iron-magnesian metamor...

The shortage of liquid and gaseous fossil fuels in the world growing day by day has led to intensive searches for new energy sources. The focus on solid fuels has increased dramatically, particularly on oil shales and brown coals, the world reserves of which significantly exceed the known reserves of liquid hydrocarbons combined. Moreover, solid...

The results of the study of the distribution of gold and silver in the main sulfide minerals of the Kadjaran mine of the copper-molybdenum-porphyry formation are presented. The regularity of the behavior of gold and silver was revealed and a forecast estimate of the gold-silver content of the lower horizons of the deposit was given. Gold and silver...

The territory of the Republic of Armenia is very rich with ores and different types of deposits, including resources of natural mineral pigments. They differ by large variation of colours and are represented by painted ores, clays, and earths, among which the most significant is the group of paints with yellow, red and brown shades (ochre). Vayots...

Study of the medieval Armenian manuscripts shows the importance of analyzing various recipes of ink preparation in their chronological sequence. The initial raw was fine ground charcoal or soot, on later stages - irongall ink was invented. The ancient Armenian recipes provide a good opportunity of tracing all the stages of improving the ink prepara...

The thermal degradation of cellulose is an important process in several fields such as the paper industry, biomass combustion, fire retardation, etc. Paper consists mostly of cellulose fibres. Although the fibre source has changed continiously from cotton or linen rags to wood, its nature is still vegetal. Pyrolysis in combination with gas chromato...

The results of the analysis on some fragments of bronze belts and a bowl discovered from southwestern Armenia at the Yegheghnadzor archaeological site are discussed. The samples are dated to the 7–6th millennium BCE from the Urartian period. The artefacts were corroded, and a multilayer structure was formed. To study the stratigraphy of layers and...

The results of the analysis on some fragments of bronze belts and a bowl discovered from southwestern Armenia, Yegheghnadzor archaeological site, are discussed. The samples are dated to the 7-6 BCE from the Urartian period. The artifacts were corroded and a multilayer structure was formed. To study the stratigraphy of layers and their composition t...

The present poster concerns the presentation of the chemical analysis on an unpublished piece of wall painting discovered during Soviet-era excavations at the site of Arin-berd/Erebuni, an Urartian fortress located in the southeast outskirts of the capital of Armenia, Yerevan. This panel is very important because it was discovered beneath another p...

The hill of Arin-berd is located in the south-eastern periphery of Yerevan, the capital of Armenia, on the northern edge of the Ararat Valley (Figure 1). On the hilltop are the ruins of a fortress built by the Urartian king Argišti I (785/780-756 BC). The fortress has been identified with certainty as corresponding to ancient Er(e)buni, which is me...

The interest of this research derived from the request for a scientific investigation of the observed phenomenon from a few contemporary artists who, in some occasions, observed the formation of craquelure in pentimento areas where a paint layer of different colour was over imposed to a zinc white layer, on commercial canvases. To investigate this...

The manuscript of Edessa or ms. 3290, a XVIII century Armenian manuscript kept at Biblioteca Universitaria di Bologna, has been thoroughly studied from the religious, artistic, historical and diagnostic point of view. Non-invasive measurements on the miniatures have been carried out in situ with portable instruments in order to evaluate the pictori...

There have been comparatively few investigations reported of radiation effects in zeolites, although it is known that these materials may be modified substantially by exposure to ionizing radiation. Thus, by exposure to γ-rays or high-energy particles, the charge states of atoms may be changed so to create, and accumulate, lattice point defects, an...

The present study relates to the problem of the thermal stability of simple chiral molecules. Rough estimates of the temperatures under which the chirality phenomenon could survive have been reported. The chiral molecules tested in the present study were 1-phenylethanol (PE) enantiomers [(S(−)- and R-(+)-], S-(−)-1-phenylpropanol [PPe] and S-(+)-tr...

Naphthalene is an interesting candidate to study in the framework of organic delivery to planetary surfaces as well as in the origin of life. Additionally, naphthalene is of environmental interest, because of its chronic and acute effects on living systems, such as humans and animals (e.g. moths). Naphthalene has been well studied in both fields. I...

Pyrolysis of S-1-phenylethanol (PE) with and without catalysts at different temperatures (80–600°C) has been carried out. In the presence of catalysts the partial racemization (≤25%) and formation of products like styrene, acetophenone and chiral benzylic ethers formation have been detected. Without a catalyst almost no racemization was observed an...

The electronic structure of epichlorohydrin is investigated in the whole valence region by a combined experimental and theoretical study. The issue of controversial assignments of the molecular electronic structure is here addressed. Photoelectron spectra (PES) and Threshold Photoelectron spectra (TPES) of room temperature molecules in the gas phas...

The idea that extraterrestrial delivery of organic matter played an important role in prebiotic evolution depends on the capability of the biomolecules to survive at high temperatures, taking into account the fact that to reach the earth the space bodies can be exposed to a significant heat up. It has also been suggested that the chiral molecules o...

Pyrolysis of 1-phenylethanol (PE) enantiomers [(S) and (R)] with and without catalysts at different temperatures (200–700°C) has been carried out. In the presence of catalysts the partial racemization (≤25%) and formation of products like styrene, acetophenone, benzaldehyde and chiral benzylic ethers formation have been detected. Without a catalyst...

The aim of the present work is to analyze the influence of temperature and minerals such ilmenite, Mg 2 Si, SiO 2 :MgO:Fe 2 O 3 , etc. on the decomposition and the racemization of the most simple chiral aromatic molecule, i.e. (R+)-and (S-)-1-phenylethanol (Pe-OH). To investigate this phenomena the minerals are deposited on the quartz liner of the...

A set of inks was analyzed using Py/GC/MS technique. They were prepared following some ancient Armenian recipes and then analyzed after being dried in air to obtain solid samples. A simple analytical procedure was adopted which excludes any treatment of the samples and consists in introducing the solid sample directly into the injector of the furna...

The thermal degradation of cellulose is an important process in several fields such as the paper industry, biomass combustion, fire retardation, etc. Paper consists mostly of cellulose fibres. Although the fibre source has changed continiously from cotton or linen rags to wood, its nature is still vegetal. Pyrolysis in combination with gas chromato...

In the last years particular attention has been dedicated to the analysis of iron-gall inks for their effects on the degradation of paper. Mainly spectroscopic techniques devoted to the determination of iron have been studied, while a minor attention has been dedicated to the organic components.In this study we propose THM pyrolysis as a rapid tool...

Laser ablation of targets of carbonaceous matter containing carbyne nanodomains (the sp hybridised carbon chains) or targets of C60 photopolymer produced carbon clusters which have been detected by FT-ICR (Fourier-Transform Ion Cyclotron Resonance) mass spectrometer. When the carbonaceous matter containing carbyne has been employed as laser target,...

The treatment of the terpene beta(-)pinene with gamma radiation (at dose level: 150, 300 and 600 kGy) causes its polymerization into a resin and into a dimer. The yield of the resin and of the dimer appears to be linearly dependent to the radiation dose. The structure of the products was studied by FT-IR spectroscopy also in comparison to a referen...

A laser abilation/Fourier-transform ion cyclotron resonance mass spectrometry was used to generate fullerenes clusters from targets of carbonaceous material containing carbyne, C-60 photopolymer, graphite, diamond, C-60 fullerene crystals.

The polyynes in heptane solution were γ‐radiolyzed at a total dose of 150, 300 and 600 kGy. After radiolysis the products were analyzed by electronic absorption spectroscopy, by HPLC (liquid chromatography) and by FT‐IR spectroscopy. Even at 150 kGy the polyynes disappear completely from the solution and the chromatographic analysis shows that the...

β(-)Pinene was treated with γ radiation at three dose levels: 150, 300 and 600 kGy. The expected effect of radiation at these high doses was the partial racemization of the substrate as already observed in the case of other terpene monomers. Unexpectedly β(-)pinene underwent a radiopolymerization reaction into a solid resin and into a dimer. The st...

Summary The degradation of a mixture of 18 different polycyclic aromatic hydrocarbons (PAHs) has been studied in acetonitrile solution by usingg-radiation at radiation doses of 100, 200 and 300 kGy. The mixture of radiolyzed PAHs was analyzed by liquid chromatography (HPLC) using a diode array detector. Radiolysis at 100 kGy total dose is already...

In the past centuries inks were prepared using many different recipes and contained a great variety of ingredients. This work presents analyses of some substances, which were used in addition to the common components of inks such as gallnuts, vitriol and charcoal, in the course of ink preparation. Qualitative characterization of seeds and peel of p...

The results of dielectric properties and direct current specific electric conductivity measurements in Armenian natural clinoptilolite samples are presented. Electron irradiation with energy 8 MeV and thermal treatment of samples are performed to elucidate possible enhancement mechanisms of clinoptilolite parameters. The results are discussed on th...

Infrared (IR) absorption and luminescence in chemically and radiation-modified natural Armenian Zeolite (clinoptilolite) samples have been studied. The luminescence was studied in 390–450 nm and 620–710 nm wavelength bands, and the IR measurements were carried out in the 400–5400 cm−1 range. It is shown that the luminescence intensity depends on th...

The sorptive behaviour of radioactive waste on Armenian zeolites, natural, irradiated, chemically treated and heated at high temperatures was studied and their capacity for the separation and enrichment of radionuclides was evaluated. The influence of temperature, acidity, basicity, specific activity, electron and gamma irradiation on sorption have...

Summary The sorptive behavior of tritiated water on natural, irradiated, chemically treated and heated at high temperatures Armenian zeolites was studied and their capacity for the separation and enrichment of tritiated water was evaluated. The distribution coefficients from the batch experiments were calculated for different zeolites and vary betw...

The abiotic origin of some biologically active molecules and macromolecules have been reviewed. Particular emphasis has been dedicated to the formation of aminoacids and about the possible mechanisms for their asymmetric synthesis and accumulation. The phenomenon of racemization has been explained in detail and then applied in the context of the ph...

Three isomeric chiral terpenes, R(+)-limonene, S(-)-limonene and R(-)-a-phellandrene were γ-radiolyzed in sealed vials at room temperature with a total radiation dose of 317 kGy. The radiolyzed samples were analyzed by FT-IR, electronic absorption spectroscopy, liquid chromatography using a diode-array detector (HPLC-DAD) and by polarimetry. Despit...

Anthracite coal and oil bitumen were submitted to γ-radiation at a total dose of 1 MGy and the radiation-processed samples were studied by FT-IR spectroscopy, thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The coal samples were studied also by TGA coupled with FT-IR spectroscopy of the evolved gases. Thermal analysis has...

Astrophysical and cosmochemical data show that many kinds of hydrocarbons are widespreaded in space, including giant molecular clouds (GMC), diffuse interstellar medium, comets, interplanetary dust particles and carbonaceous meteorites. Here effort is made to show a close relation between high-molecular weight hydrocarbons, observed in space and ex...

Astrophysical and cosmochemical data show that many kinds of hydrocarbons are widespread in space, including giant molecular clouds, diffuse interstellar medium, comets, interplanetary dust particles, and carbonaceous meteorites. Here an effort is made to show the close relation between high-molecular weight hydrocarbons observed in space and exist...

In this communication we present the basic concept that the pure PAHs (Polycyclic Aromatic Hydrocarbons) can be considered only the ideal carriers of the UIBs (Unidentified Infrared Bands), the emission spectra coming from a large variety of astronomical objects. Instead we have proposed that the carriers of UIBs and of protoplanetary nebulae (PPNe...

Clinoptilolite is widely known for their uses especially in environmental applications. They have been utilized.in nuclear wastewater treatment and in land restoration. Irradiation emitted by nuclear liquid waste includes α, β and γ radiation. Irradiated clinoptilolite may exhibit crystal changes which affect the sorption of Cs+ and Sr2*. Sorption...

A relatively heavy petroleum fraction called distillate aromatic extract (DAE) which has been proposed to be the carrier of the emission bands of certain astronomical objects like protoplanetary nebulae (PPNe) and the so-called unidentified infrared bands (UIBs), has been radiolyzed with -radiation to a total dose of 1 MGy. The stability of DAE tow...

It is of paramount importance to detect traces of life on Mars surface. Organic molecules are highly polar and if present on Mars require to be extracted from the dust sample, separated, concentrated, processed and analysed by an appropriate apparatus. PRE-ADAMO (PRebiotic Experiment - Activity of Dust And bioMolecules Observation) is a multi-steps...

The Fourier-transform infrared spectra and the electronic spectra of a series of petroleum fractions of different composition and origins have been studied. Furthermore, these fractions have been modified through the Scholl reaction, a reaction that causes an increase in the aromatic content of the fractions by causing the formation of polycyclic a...

Many efforts to attribute Unidentified Infrared Bands (UIBs) spectral features to a given carrier (e.g. PAHs) have been unsuccessful. Recently, however, Cataldo, Keheyan, Heymann(2002) proposed a new model for the interpretation of UIBs: they studied a mixture of different groups of molecules, namely, petroleum and processed aromatic, naphtenic (cy...

Polymeric fullerene oxide (PFO) prepared by prolonged ozonation of C60 fullerene has been laser irradiated and the resulting products formed have been studied by ion cyclotron resonance mass spectrometry. It has been found that PFO produces a complete set of carbon clusters from C60 up to C164. The mechanism of formation of this set of fullerenic c...

It is shown by FT-ICR (Fourier transform ion cyclotron resonance) mass spectrometry that carbon clusters considered to be the superior homologues of C60 fullerene are formed by laser irradiation of both synthetic diamond grains or from pure C60 fullerene crystals. The surfaces of the laser irradiated diamond or C60 have been examined by Raman spect...

The knowledge about carbon allotropy and carbon black and some selected recent discoveries in carbon science have been reviewed in the present paper. The topic has been discussed from an interdisciplinary perspective with a special emphasis on the application of these discoveries in the context of the structure of the interstellar carbon dust. This...

Natural zeolites from Armenia modified by chemical treatment and electron irradiation were studied for water and benzene vapor absorption and structural change. A significant influence of irradiation on the sorption property of zeolites was obtained: with increase of the irradiation dose the sorption of water vapors increased, while for benzene vap...

It is shown that all the pseudohalogens belonging to the series of sulfur dicyanide Sy(CN)2 or thiocyanogens polymerise very easily in the dry state, under moderate heating to produce a series of brick-red or orange solids known as polythiocyanogens with the general formula [Sy(CN)2]x with y an integer 1, 2, 3, 4. It is shown by FT-IR, electronic s...

In this work we started from the basic idea that the pure polycyclic aromatic hydrocarbons (PAHs) cannot be the real carriers of the unidentified infrared bands (UIBs), the emission spectra coming from a large variety of astronomical objects. Instead we propose a new model taken from petroleum chemistry which, we can show, is able to match both the...

Laser ablation of targets of carbonaceous matter containing carbyne nanodomains (the sp hybridised carbon chains) or targets of C60 photopolymer produced carbon clusters which have been detected by FT-ICR (Fourier-Transform Ion Cyclotron Resonance) mass spectrometer. When the carbonaceous matter containing carbyne has been employed as laser target,...

Laser ablation of targets of carbonaceous matter containing car-byne nanodomains (the sp hybridised carbon chains) or targets of C 60 photopolymer produced carbon clusters which have been detected by FT-ICR (Fourier-Transform Ion Cyclotron Resonance) mass spectrometer. When the carbonaceous matter containing car-byne has been employed as laser targ...

Carbon_Allotropy_and_Carbon_Dust_in_the

Graphite and carbon black samples were laser ablated in an FT-ICR (Fourier transform-ion cyclotron resonance spectrometer) by Nd-YAG laser under high vacuum in conditions recalling those existing in the interstellar medium. It is shown that graphite gives a regular sequence of polyyne and cyclopolyyne chains from C10 to C27 and additionally produce...

In this communication we introduce a new project on the study of the physico-chemical processes relevant to the understanding of the origin of life. Energetic radiations and gas phase reactions are two essential active mechanisms in space in producing complex molecules. Reactions involving PAHs, fullerenes, grains and several types of neutrals will...

The reactivity of naphthalene and pyrene radical cations and their derivatives , has been studied with molecules of interstellar interest in an ion cyclotron resonance apparatus. The radical cations and are unreactive with H2,CO,H2O and NH3. Adduct formation is the only channel for almost all reactions of with these molecules. The implications of t...

Ion-molecule radiative association reactions are considered to be of relevant importance in the interstellar medium. First results on radiative association rate coefficients were obtained with ion cyclotron resonance (ICR) technique. In an ICR apparatus the pressure can be varied over a wide range, and direct information on the radiative and ternar...

Obsidians from occurrences located in Armenia have been analysed using neutron activation analysis, both instrumental and epithermal, in order to enhance the knowledge of characteristics of potential sources of raw material exploited during prehistory. An alternative characterization technique, the fission-track dating method, was also applied. Res...

The chemistry of naphthalene radical cation and its derivatives (C10Hn+, n = 6,7,8,9) has been studied with molecules and atoms of interstellar interest in a selected ion flow tube. The radical cation C10H8+ is unreactive with H2, CO, H2O, and NH3 but reacts with H, O, and N atoms. Adduct formation is the only channel detected in the case of reacti...

The chemistry of the pyrene radical cation C16H10+ and its derivatives C16H9+ and C16H11+ has been investigated in the gas phase using a flowing afterglow-selected ion flow tube. Rate coefficients have been determined for reactions between C16Hn+ (n = 9, 10, 11) and H2, CO, H2O, and NH3 molecules as well as H, O, and N atoms. These studies suppleme...

The chemistry of the pyrene radical cation C16H10+ and its derivatives C16H9+ and C16H11+ has been investigated in the gas phase using a flowing afterglow-selected ion flow tube. Rate coefficients have been determined for reactions between C16Hn+ (n = 9, 10, 11) and H2, CO, H2O, and NH3 molecules as well as H, O, and N atoms. These studies suppleme...

Abstract The chemistry of the pyrene radical cation C H and its derivatives C H and C H has been investigated in the gas 16 10 16 9 16 11 phase using a flowing afterglow-selected ion flow tube. Rate coefficients have been determined for reactions between C16H n (n 9, 10, 11) and H2, CO, H2O, and NH3 molecules as well as H, O, and N atoms. These stu...

Diffuse interstellar bands (DIBs) are mysterious absorption lines in the optical spectra of stars, and have been known for 75 years. Although it is widely believed that they arise from gas-phase organic molecules (rather than from dust grains) in the interstellar medium, no consensus has been reached regarding their precise cause. The realization t...