George Kitis

George Kitis

Aristotle University of Thessaloniki

H-index: 45

Europe-Greece

About George Kitis

George Kitis, With an exceptional h-index of 45 and a recent h-index of 25 (since 2020), a distinguished researcher at Aristotle University of Thessaloniki, specializes in the field of Thermoluminescence, Optically and InfraRed Stimulated Luminescence, Radiation Dosimetry and Dosimetric Methods of Dating.

His recent articles reflect a diverse array of research interests and contributions to the field:

Simulation study of a nanomaterial interacting with ionizing radiation through OTOR and IMTS models for different particle sizes

Optimization of an experimental TL protocol for discriminating the recombination pathways

LUMINESCENCE DATING OF LIMESTONE WALLS AND POTTERY FROM ITHACA (SCHOOL OF HOMER); FIRST AGES.

Are there discrete recombination pathways in the case of semi-localized thermoluminescence transitions: The significance of thermal treatments towards their discrimination

TL-SDA: A designed toolkit for the deconvolution analysis of thermoluminescence glow curves

The effect of particle size on the radiation dose response of luminescence signals from nanophosphors

Simulation of thermoluminescence signals at very low dose rates and low doses: Implications for dosimetric applications

Thermoluminescence and Optically Stimulated Luminescence properties of in-vitro aged dental porcelain

George Kitis Information

University

Aristotle University of Thessaloniki

Position

___

Citations(all)

8423

Citations(since 2020)

3426

Cited By

6025

hIndex(all)

45

hIndex(since 2020)

25

i10Index(all)

162

i10Index(since 2020)

97

Email

University Profile Page

Aristotle University of Thessaloniki

George Kitis Skills & Research Interests

Thermoluminescence

Optically and InfraRed Stimulated Luminescence

Radiation Dosimetry and Dosimetric Methods of Dating

Top articles of George Kitis

Simulation study of a nanomaterial interacting with ionizing radiation through OTOR and IMTS models for different particle sizes

Authors

E Tsoutsoumanos,T Karakasidis,N Laskaris,PG Konstantinidis,GS Polymeris,G Kitis

Journal

Materials Research Bulletin

Published Date

2024/2/1

A correlation linking nanocrystal dimensions, and thermoluminescence (TL) signal magnitude has been extensively reported in the scientific literature, while the underlying physical mechanisms remain relatively unexplored. The present study aims to investigate these mechanisms through simulations conducted in Python. Two mathematical models, the One Trap – One Recombination (OTOR) center and the Interactive Multi-Trap System (IMTS), were used to derive theoretical luminescence signals. The simulations were designed to replicate nanomaterials of different sizes by adjusting the quantity of available electron traps, also for phenomena related to weak or strong competition. The obtained results were meticulously compared with experimental data derived from actual nanostructured thermoluminescent dosimeters (TLDs), instigating a thorough comparative discussion. The OTOR model demonstrated its …

Optimization of an experimental TL protocol for discriminating the recombination pathways

Authors

Pavlos G Konstantinidis,GS Polymeris,E Tsoutsoumanos,G Kitis

Journal

Applied Radiation and Isotopes

Published Date

2024/1/1

The present work investigates an altered version of an already existing protocol that was utilized to study in depth the underlying mechanisms and phenomena of stimulated luminescence based on three phenomenological models. These phenomena are related to electron recombination pathways, including de-localized, localized, or semi-localized transitions. This new experiment consists of one new protocol, that requires prior specific heating treatments. It includes sets of 5 measurements per heating cycle and uses prompt isothermal decay (PID) following certain preheats under single high doses. The materials that are under study are the MgB4O7: Dy, Na (MBO) and BeOR, both having a localized peak in their dosimetric region. The protocol enables the examination of the recombination mechanisms of the traps and their trapping parameters, while also providing the ability to observe any potential transition …

LUMINESCENCE DATING OF LIMESTONE WALLS AND POTTERY FROM ITHACA (SCHOOL OF HOMER); FIRST AGES.

Authors

V. Liritzis,I.,Vafiadou,A.,Polymeris,G.S.,Kitis,G.,Iliopoulos,I.,Xanthopoulou

Journal

DOI: 10.5281/zenodo.10622009

Published Date

2024/2

Age estimation of two carbonate rock samples, using thermoluminescence (TL) technique, and two ceramic sherds using optically stimulated luminescence (OSL) was performed; all derived from School of Homer (Pelikata), on Ithaca Island, Greece. The first stone sample was collected from the east façade, the lower row of the Mansion (ITH-3), while sample ITH-4 derives from the outer circular wall of well-known archaeological age. The partial bleaching methodology of surface luminescence dating method using fine powder was applied for the equivalent dose determination. The ages given by the two carbonate rock samples (stairs and wall) were in the 2nd and 1st millennia BC; the two ceramics dated to late Byzantine era. Various experimental features concerning bleaching of the carbonate rock samples are discussed.

Are there discrete recombination pathways in the case of semi-localized thermoluminescence transitions: The significance of thermal treatments towards their discrimination

Authors

PG Konstantinidis,GS Polymeris,E Tsoutsoumanos,G Kitis

Journal

Physica B: Condensed Matter

Published Date

2024/4/1

This study explores an advanced luminescence protocol, aiming to reveal recombination mechanisms behind stimulated luminescence in MgB4O7: Dy, Na (MBO), and BeO: Cr, Mg, Sn (BeOR). The two-stage protocol integrates elements from prior methodologies. In the initial phase, materials undergo precise annealing at varying temperatures, followed by Thermoluminescence (TL) measurements. The second stage involves repeating annealing procedures with a single high dose. Materials exhibit localized peaks within dosimetric regions. The analysis reveals MBO's two distinct excited states, valuable for understanding recombination mechanisms and potential transitions. While BeOR undergoes a complete transition, MBO shows indications of a similar transformation. The confirmed presence of two distinct excited states within MBO establishes a fundamental premise. Validation includes peak shape methods …

TL-SDA: A designed toolkit for the deconvolution analysis of thermoluminescence glow curves

Authors

AM Sadek,MA Farag,AI Abd El-Hafez,G Kitis

Journal

Applied Radiation and Isotopes

Published Date

2024/4/1

In the present study, a graphical user interface (GUI) toolkit has been developed to analyze the thermoluminescence (TL) glow-curve and evaluate the trapping parameters using TL expression based on the one-trap one-recombination model. The basic idea of the deconvolution analysis in the developed toolkit is based on performing a sequence of successful fits, where the information provided by each fit is used by the next fit until the deconvolution of the entire glow curve approaches an optimum solution. The starting values and ranges of the fitting parameters can be controlled and adjusted to improve the deconvolution analysis of complex structure glow curves. The designed toolkit is also supported by the background-subtraction option to improve the analysis at low irradiation dose levels. The expanded uncertainty at the 95 % confidence level of the fitted trapping parameters is also provided. All the …

The effect of particle size on the radiation dose response of luminescence signals from nanophosphors

Authors

Vasilis Pagonis,George S Polymeris,George Kitis,PD Sahare

Journal

Radiation Measurements

Published Date

2023/8/1

The development and study of new nanomaterials for luminescence dosimetry is an active research area in materials science, with new nanomaterials introduced for both thermoluminescence dosimetry (TLD), and optically stimulated dosimetry (OSLD). Experimental work shows that the radiation dose response of luminescence signals from nanomaterials depends on the particle size, however there have been no quantitative descriptions of these particle size effects. In this paper we use the defect interaction model (DIM) to describe the effect of particle size on the dose response of luminescence signals from nanodosimetric materials. The model evaluates the variation of the luminescence signal with the particle size from the nanoregion of 10–100 nanometers, up to the microregion with diameters of tens of micrometers. The model describes in a quantitative manner the following experimental observations: (a) An …

Simulation of thermoluminescence signals at very low dose rates and low doses: Implications for dosimetric applications

Authors

George Kitis,Vasilis Pagonis

Journal

Radiation Physics and Chemistry

Published Date

2023/8/1

During luminescence dosimetry applications, samples are irradiated in the laboratory with irradiation dose rates of the order of 0.1 Gy/s. By contrast, samples in nature are irradiated with a dose rate many orders magnitude smaller, typically 1 mGy/year. In this paper, the effect of very low dose rates and also low doses on thermoluminescence (TL) signals is investigated using the basic one-trap one-recombination center model (OTOR). The simulations showed that at very low dose rates the assumptions of quasi-equilibrium conditions (QE) are violated. This violation of QE conditions results in a significant distortion of the shapes of TL glow curves, with the result that the peak shape methods of analysis fail to produce the correct activation energy E of the traps. At the same time, the estimated half-life of the electrons traps is found to increase significantly at very low doses. The dose response of the sample at very low …

Thermoluminescence and Optically Stimulated Luminescence properties of in-vitro aged dental porcelain

Authors

M Pal,U Pal,V Chernov,R Meléndrez,M Barboza-Flores

Journal

Journal of nanoscience and nanotechnology

Published Date

2009/3/1

The thermoluminescence (TL) and optically stimulated luminescenece (OSL) response of TiO2:Yb nanoparticles are studied. After beta irradiation, the materials developed a significant TL/OSL signal associated to several localized trapping states around 360–620 K. The OSL signal is mainly due to the releasing of trapped charges in the low temperature (360 and 460 K) trapping states. A computer glow curve deconvolution procedure was used to determine the activation energies and kinetic order of the TL processes.

Nanostructured TLDs: Studying the impact of crystalline size on the Thermoluminescence glow-curve shape and electron trapping parameters

Authors

E Tsoutsoumanos,M Saleh,PG Konstantinidis,V Altunal,PD Sahare,Z Yengigil,T Karakasidis,G Kitis,GS Polymeris

Journal

Radiation Physics and Chemistry

Published Date

2023/11/1

Nanostructured thermoluminescent dosimeters (TLDs) and their relevance in the field of Stimulated Luminescence has grown over the past years. Particularly, since preparation methods and characterization techniques have been improved, while their integration in technological advancements which has also significantly increased. Despite the numerous case studies dealing with applications and properties of nanomaterials, there is a limited number of studies investigating cases from a basic research point of view, like studying the transition of a material from bulk to nanoscale and the dominant features of this transition. Specifically, in Thermally Stimulated Luminescence or Thermoluminescence (TL), the extensive study via geometrical signal processing with the well-established techniques of Peak Shape Methods (PSM) and Computerized Glow-Curve Deconvolution (CGCD), and the estimation of trapping …

On the Need for Deconvolution Analysis of Experimental and Simulated Thermoluminescence Glow Curves

Authors

George Kitis,Vasilis Pagonis

Journal

Materials

Published Date

2023/1/16

Simulation studies of thermoluminescence (TL) and other stimulated luminescence phenomena are a rapidly growing area of research. The presence of competition effects between luminescence pathways leads to the complex nature of luminescence signals, and therefore, it is necessary to investigate and validate the various methods of signal analysis by using simulations. The present study shows that in simulations of luminescence signals originating from multilevel phenomenological models, it is not possible to extract mathematically the individual information for each peak in the signal. It is further shown that computerized curve deconvolution analysis is the only reliable tool for extracting the various kinetic parameters. Simulation studies aim to explain experimental results, and therefore, it is necessary to validate simulation results by comparing with experiments. In this paper, testing of simulation results is performed using two methods. In the first method, the influence of competition effects is tested by comparing the input model parameters with the output values from the deconvolution analysis. In the second method, the agreement with experimental results is tested using the properties of well-known glow peaks with very high repeatability among TL laboratories, such as the 110 °C glow peak of quartz.

Discovering excited states; an innovative technique for the study of recombination pathways

Authors

PG Konstantinidis,E Tsoutsoumanos,GS Polymeris,G Kitis

Journal

Radiation Physics and Chemistry

Published Date

2023/11/1

This study introduces a new experimental approach to investigate the stimulated luminescence of three different materials: LBO (LiB4O7: Cu, In), MBO (MgB4O7: Dy, Na), and BeOR (BeO: Cr, Mg, Sn). The goal is to utilize three phenomenological models (localized, de-localized, and semi-localized) to explore recombination pathways, specifically the two mechanisms where electrons follow either the conduction band or an excited state. The modified protocol includes a single high dose with continuous Prompt Isothermal Decay (PID) measurements, allowing for two different methods to be used simultaneously in the resulting signal. The study concludes that the protocol can effectively analyze the recombination pathways of all three materials, with a focus on BeOR's potential transition between localized and de-localized mechanisms. This result strengthens the combined phenomenological model and highlights the …

Thermoluminescence study on materials used in restorative dentistry for personal dosimetry applications

Authors

P Taiganidis,IK Sfampa,L Malletzidou,PG Konstantinidis,E Kontonasaki,G Kitis

Journal

11th International Conference of the Balkan Physical Union

Published Date

2023/10

Thermoluminescence study on materials used in restorative dentistry for personal dosimetry applications - NASA/ADS Now on home page ads icon ads Enable full ADS view NASA/ADS Thermoluminescence study on materials used in restorative dentistry for personal dosimetry applications Taiganidis, P. ; Sfampa, IK ; Malletzidou, L. ; Konstantinidis, PG ; Kontonasaki, E. ; Kitis, G. Abstract Publication: 11th International Conference of the Balkan Physical Union Pub Date: October 2023 Bibcode: 2023ibpu.confE..29T No Sources Found © The SAO/NASA Astrophysics Data System adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A NASA logo Smithsonian logo Resources About ADS ADS Help What's New Careers@ADS Social @adsabs ADS Blog Project Switch to full ADS Is ADS down? (or is it just me...) Smithsonian …

Standardizing the computerized analysis and modeling of luminescence phenomena: New open-access codes in R and Python

Authors

Vasilis Pagonis,George Kitis

Journal

Radiation Measurements

Published Date

2022/4/1

In this paper we describe a new initiative for the development of open-access codes in R and Python, to be used for computerized analysis and modeling of luminescence phenomena. The purpose of this broad initiative is to help in the classification, organization and standardization of the computerized analysis and modeling of a wide range of luminescence phenomena. Although a very significant number of such open access codes is already available in the literature, there is a lack of common standardization and homogeneity in the nomenclature and in the codes, which we hope to address. New open-access codes are developed for thermoluminescence (TL), isothermal luminescence (ITL), optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), dose response (DR) and time-resolved (TR) signals. In each of these categories, computer codes are currently being developed based on …

Estimations of 137Cs activity concentrations using marine parameters issued from MODIS and Copernicus Marine Environment Monitoring Services (CMEMS) data …

Authors

Georgia Mavrokefalou,Olga Sykioti,Georgios Kitis,Heleny Eleni Florou

Journal

Environmental Science and Pollution Research

Published Date

2022/7

Cesium-137, as the main fission product, is of special interest in the marine environment because of its solubility, which results to very low sinking time. Nevertheless, the conservative form of the main percentage of 137Cs introduced in the marine environment (70%) makes 137Cs to be included in the salinity of sea water. Based on this property, in this study, we examine potential relations between 137Cs activity concentrations and marine parameters issued from Earth Observation (EO) data products in the Southern Aegean Sea, in order to investigate the possibility of 137Cs to be recorded by satellite data. In particular, measurements of physical and biological marine parameters issued from the Copernicus Marine Environment Monitoring Service (CMEMS) database and MODIS ocean products are retrieved for the dates of 137Cs field measurements. Single and multiple regression analyses are performed …

Testing new analytical expression for dose response curves originating from the OTOR model

Authors

George Kitis,Jun Peng,Bo Li,Vasilis Pagonis

Journal

Journal of Luminescence

Published Date

2022/4/1

The possibility of precisely evaluating the equivalent beta dose in stimulated luminescence dating depends on the ability to fit the constructed dose response calibration curve with appropriate analytical expressions. There are a number of such expressions which successfully fit the dose response calibration curves. In the present study we use the recently developed analytical Pagonis-Kitis-Chen equation (PKC equation) to describe the dose response curves from a set of single-grain experimental data for a sedimentary sample from the Haua Fteah Cave in Libya. The PKC equation describes in analytical form the rate of filling of the electron traps during the irradiation stage in the one trap one recombination center model (OTOR). A detailed comparison was carried out between the PKC equation and two very successful equations existing in literature. The comparison criteria were the values of: (a) the reduced chi …

Implementation of expressions using Python in stimulated luminescence analysis

Authors

K Prevezanou,G Kioselaki,E Tsoutsoumanos,PG Konstantinidis,GS Polymeris,V Pagonis,G Kitis

Journal

Radiation Measurements

Published Date

2022/6/1

In Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL), the study of complex experimental TL glow curves and OSL signal processing, also known as deconvolution, was revolutionized by using a single, analytic master equation described by Lambert W function. This latter equation has been also adopted for the case of dose response fitting. The present study exploits the utilization of Lambert W function in Python programming environment. These analytic expressions are based on One Trap-One Recombination center (OTOR) and Two Traps-One Recombination center (TTOR) models. Python scripts, with corresponding software flowchart being described in general, are created to deconvolve TL, LM-OSL, CW-OSL as well as to fit dose response experimental data. The calculated results are in agreement with those of the existing literature. Also, all scripts are free and available in GitHub to the …

Recombination pathways in a BeO yielding two main dosimetric TL peaks

Authors

PG Konstantinidis,E Tsoutsoumanos,GS Polymeris,G Kitis

Journal

Radiation Measurements

Published Date

2022/2/1

Apart from the commercially used Thermalox, BeOR is a new type of Beryllium Oxide fabricated by a different company in Turkey. As it is shown by other groups, this dosimeter yields two overlapping main dosimetric TL peaks in the temperature region of 100–300 °C and one peak at 350 °C. The aim of the present study is the calculation of the activation energies of these two peaks with the use of specific protocols, including the Fractional Glow Technique (FGT), an Isothermal Decay signal (PID) and the Peak Shape Methods (PSM). Also, these experimental procedures were conducted in two different readers, namely the Harshaw and the Risø reader, for better repeatability and in order to minimize the error of the calculations. Moreover, another goal is to correlate the activation energy values with the recombination pathways that are present in the BeOR and its corresponding peaks. Specifically, both peaks have …

Aristotle University of Thessaloniki, Physics Department, Nuclear Physics and Elementary Particle Physics Section, Thessaloniki, Greece

Authors

George Kitis

Journal

Radiation Dosimetry Phosphors: Synthesis, Mechanisms, Properties and Analysis

Published Date

2022/5/31

The TL andwww OSL belong to the category of the passive dosimetric methods. The corresponding passive detectors are mainly artificial and natural inorganic crystals. The core element of the passive TL and OSL methods is the existence of at least one long lived energy level. In the framework of the energy band model in solids, lattice defects and various impurities cause such energy levels within the forbidden band. The electron and holes created and liberated during irradiation are trapped within these energy levels bringing the crystal into an excited state. The time the crystal remains in the excited state is termed lifetime with values ranging from microseconds to billions of years. The passive TL and OSL detectors are exclusively based on this property. This is the origin of the necessity to estimate the physical characteristics of the trapping states leading to the development of a special and extensive research topics in TL and OSL fields. In TL and OSL terminology the trapping states of electrons are called electron traps and the trapping states of holes are called luminescence centers. The TL and OSL photons results when trapped electrons are stimulated to escape from the traps and to recombine with holes at luminescence centers. In the case of TL the stimulation is heat and the physical characteristics of the trapping states are the activation energy E on (eV) and the frequency factor s in (s− 1). In the case of OSL the stimulation is optical photons and the physical characteristics is the optical ionization cross section and the optical trap depth. This chapter will present the methods used to evaluate the physical characteristics of the trapping …

Analysis of complex stimulated luminescence (SL) curves using analytical solutions of the one trap one recombination (OTOR) center model

Authors

George Kitis

Published Date

2022/1/1

Thermoluminescence (TL) and optically stimulated luminescence (OSL) are widely applied passive radiation dosimetry methods. In most cases all experimental TL and OSL curves are complex, consisting of many overlapping single components. The useful physical information included in each curve include (a) the intensity of a specific component, which is used as a radiation dosemeter and (b) the physical parameters associated with the energy levels responsible for the individual components of these complex experimental curves. Both information is extracted by the computerized curve deconvolution (CCD), which analyses the complex curves into individual components. The cornerstone of the CCD technique is the model expression describing one single component. The main goal of this chapter is to provide a review on recently developed physical and not empirical equations termed master equations. The …

Simulation of the effect of resolution between thermoluminescence peaks on the initial rise method of analysis

Authors

Georgios Kitis,A Sadek,G Polymeris,V Pagonis

Journal

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Published Date

2022/8/1

The initial rise (IR) method is an essential and accurate method for the evaluation of the activation energies of electron levels responsible for the individual glow peaks of a complex thermoluminescence (TL) glow-curve. The main drawback of the method is the reduction of its accuracy when the degree of peak overlapping within the glow curves increases. In the present work detailed simulations are performed to investigate the dependence of the accuracy of the IR method on the resolution parameter R between two or more successive peaks. During the simulations, the amount of peak overlapping is varied by keeping the parameters of one peak fixed, while varying the parameters of the rest of the peaks. Specifically, a two-peak TL glow curve is studied by (a) varying the activation energy E while keeping the frequency factor s constant and (b) by varying s while keeping E constant. In addition, a five-peak glow …

See List of Professors in George Kitis University(Aristotle University of Thessaloniki)

George Kitis FAQs

What is George Kitis's h-index at Aristotle University of Thessaloniki?

The h-index of George Kitis has been 25 since 2020 and 45 in total.

What are George Kitis's top articles?

The articles with the titles of

Simulation study of a nanomaterial interacting with ionizing radiation through OTOR and IMTS models for different particle sizes

Optimization of an experimental TL protocol for discriminating the recombination pathways

LUMINESCENCE DATING OF LIMESTONE WALLS AND POTTERY FROM ITHACA (SCHOOL OF HOMER); FIRST AGES.

Are there discrete recombination pathways in the case of semi-localized thermoluminescence transitions: The significance of thermal treatments towards their discrimination

TL-SDA: A designed toolkit for the deconvolution analysis of thermoluminescence glow curves

The effect of particle size on the radiation dose response of luminescence signals from nanophosphors

Simulation of thermoluminescence signals at very low dose rates and low doses: Implications for dosimetric applications

Thermoluminescence and Optically Stimulated Luminescence properties of in-vitro aged dental porcelain

...

are the top articles of George Kitis at Aristotle University of Thessaloniki.

What are George Kitis's research interests?

The research interests of George Kitis are: Thermoluminescence, Optically and InfraRed Stimulated Luminescence, Radiation Dosimetry and Dosimetric Methods of Dating

What is George Kitis's total number of citations?

George Kitis has 8,423 citations in total.

What are the co-authors of George Kitis?

The co-authors of George Kitis are Reuven Chen, Vasilis Pagonis, Niyazi Meric, Ebenezer Olubanji Oniya, Lamprini Malletzidou.

    Co-Authors

    H-index: 47
    Reuven Chen

    Reuven Chen

    Tel Aviv University

    H-index: 34
    Vasilis Pagonis

    Vasilis Pagonis

    McDaniel College

    H-index: 15
    Niyazi Meric

    Niyazi Meric

    Ankara Üniversitesi

    H-index: 9
    Ebenezer Olubanji Oniya

    Ebenezer Olubanji Oniya

    Adekunle Ajasin University

    H-index: 7
    Lamprini Malletzidou

    Lamprini Malletzidou

    Aristotle University of Thessaloniki

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