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Öğe A macrocyclic tetra-undecyl calix[4]resorcinarene thin film receptor for chemical vapour sensor applications(Springer, 2020) Sen, S.; Davis, F.; Capan, R.; Ozbek, Z.; Ozel, M. E.; Stanciu, G. A.This work demonstrates the fabrication of chemical vapour sensors using Langmuir-Blodgett (LB) thin films, describing the thin film properties of a tetra-undecyl calix[4]resorcinarene molecule along with a discussion of their sensing performance. Atomic Force Microscopy and Surface Plasma Resonance (SPR) methods were used for the characterization of the deposited thin films. As evidenced by these characterization methods, high quality and uniform Langmuir monolayers were formed on the water surface and can be transferred onto glass and gold-coated glass substrates with a transfer ratio of over 95%. The gas sensing properties towards the vapours of four volatile organic compounds were also examined by the SPR technique. Tetra-undecyl calix[4]resorcinarene LB thin film is sensitive to organic vapours (benzene, chloroform, ethanol and toluene) with rapid response and recovery times, demonstrating promise towards future vapour detection applications, especially for the rapid detection of leaks or spillage.Öğe Calix[4]amine Langmuir-Blodgett thin film sensing properties against volatile organic compounds(Iop Publishing Ltd, 2019) Sen, S.; Capan, R.; Ozbek, Z.; Ozel, M. E.; Stanciu, G. A.; Davis, F.Thin films of CBAMINE were deposited at air-water interface by the method of Langmuir-Blodgett (LB) technique onto a suitable substrate. Atomic force microscopy technique was used to characterize its thin film properties. The results indicate that a uniform LB film monolayer from the water surface to a glass or quartz crystal substrates deposited with a transfer ratio of over 96 %. Gas sensing properties and thickness of the LB thin films of CBAMINE were investigated using Surface plasmon resonance (SPR) technique. Its vapour sensing properties were investigated for different volatile organic compounds. Reversible changes in the optical behaviour were observed and thin films of this material are highly selective for chloroform vapour with fast response and recovery times.Öğe Characterization of Langmuir-Blodgett films of a calix[8]arene and sensing properties towards volatile organic vapors(Elsevier Science Sa, 2010) Capan, R.; Ozbek, Z.; Goktas, H.; Sen, S.; Ince, F. G.; Ozel, M. E.; Stanciu, G. A.Within this article, we report the characterization and organic vapor sensing properties of Langmuir-Blodgett (LB) thin films of calix[8]arenes. Surface pressure-area isotherms show that very stable monolayers are formed at the air-water interface. The LB film could be deposited onto different substrates which allowed the films to be characterized by UV, quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and atomic force microscopy (AFM). The results indicate that good quality, uniform LB films can be prepared with transfer ratios of over 0.95. QCM results showed that the deposited mass of calix[8]arene monolayer onto a quartz crystal decreased from 693 to 204 ng as the number of layers is increased. AFM studies showed a smooth, and void free surface morphology with a rms value of 1.202 nm. The sensing abilities of this LB film towards the development of room temperature organic vapor sensing devices are also studied. Responses of the LB films to various vapors are fast, large, and reversible. It was found that the obtained LB film is significantly more sensitive to chloroform than other vapors. It can be concluded that this molecule could have a potential application in the research area of room temperature vapor sensing devices. (C) 2010 Elsevier B.V. All rights reserved.Öğe Langmuir-Blodgett film properties of based on calix[4]resorcinarene and the detection of those against volatile organic compounds(Springer Heidelberg, 2019) Sen, S.; Capan, R.; Ozbek, Z.; Ozel, M. E.; Stanciu, G. A.; Davis, F.To determine their inherent properties, thin films of calix[4]resorcinarene (C11AMINE) were deposited using the Langmuir-Blodgett (LB) technique onto a suitable substrate. Prior to the LB thin film preparation, this molecule was first studied at the air-water interface. For the characterization of the deposited film, UV-visible absorption spectroscopy and atomic force microscopy were used. Characterization results indicated that the Langmuir monolayer can be transferred from the water surface onto a glass or a quartz substrate with a transfer ratio of over 95%. This shows that this material is suitable for the preparation of high quality, uniform LB films. Later, gas sensing properties and thickness of these thin films were investigated using the surface plasmon resonance method. Thicknesses and the refractive index values of the C11AMINE films were obtained for differing number of layers. Then, the gas sensing properties towards vapours of four volatile organic compounds were examined: chloroform, benzene, toluene and ethanol. Reversible changes in the optical behaviour of thin films of C11AMINE were observed. It is found that thin films of this material are highly selective towards chloroform vapour, with rapid response and recovery times, making them suitable for practical chloroform-detection applications.Öğe Observing the effects or rapid industrialization, on forestry and pastures by remote sensing(J D Sauerlanders Verlag, 2009) Yildirim, H.; Ozel, M. E.; Akca, A.; Ozdemir, M.Rapid and uncontrolled industrialization in an area and related population growth require fast assessments for the actual land-cover/land-use (LC/LU) maps and related practices, in order to avoid the overuse and damaging of the landscape beyond sustainability. Growth of industry, brings an increase in population beyond its needs, increasing the housing demands. All these may cause the loss of vegetation cover in the region, mostly of forestry and grassland in the present case (YILDIRIM et al., 1997, 2002). Modern remote sensing and geographic information system (GIS) technologies fit well for the evaluation and long term monitoring of such effects. In the present case, a region of Gebze County (Kocaeli-Turkey), 50 km east of metropolitan Istanbul is considered as a pilot site for long term monitoring of such rapid changes and their effects on the vegetation cover and environment. The region is observed between 1985-2005, by satellite images and quantified the LC/LU changes. Comparisons were then made among the observed patterns over these years and also between images and the land-use patterns projected by the government planning offices carried out in the region in the start of the interval considered. The LC/LU patterns quickly overshot the planned industrial and settlement areas in much less than a decade. The research work also includes an interval just before the 17 August 1999 Marmara Earthquake devastated the dwellings and roads in the area to a large extent. Therefore, the results could also be used, for a comparison of before and after earthquake inventories in many areas. The results in 2005 were indicative of rather fast recovery of the region from the negative effects of earthquake, in many respects. Further, a projection from the observed trends to the year 2010 (the next 5 years) was also made: Industrial areas are expected to increase to about 25% of all the total land area, from a start in 1986, of 2.4% to a 9% in a decade. Forests, although constitutionally protected, also may reduce to 20% (from a starting value of 30%). However the main loser among vegetation cover types was the pasture, which started at 39% in 1986 and is reduced to 5% in 2005. Extrapolation to 2010 is indicative of the possibility that no pasture area would be left in the region.Öğe Optical parameters of calix[4]arene films and their response to volatile organic vapors(Elsevier Science Sa, 2011) Ozbek, Z.; Capan, R.; Goktas, H.; Sen, S.; Ince, F. G.; Ozel, M. E.; Davis, F.The Langmuir-Blodgett (LB) technique was employed to produce thin LB films using an amphiphilic calix-4-resorcinarene onto different substrates such as quartz, gold coated glass and quartz crystals. The characteristics of the calix LB films are assessed by UV-visible, quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) measurements. UV-vis and QCM measurements indicated that this material deposited very well onto the solid substrates with a transfer ratio of >0.95. Using SPR data, the thickness and refractive index of this LB film are determined to be 1.14 nm/deposited layer and 1.6 respectively. The sensing application of calixarene LB films towards volatile organic vapors such as chloroform, benzene, toluene and ethanol vapors is studied by the SPR technique. The response of this LB film to saturated chloroform vapor is much larger than for the other vapors. The response is fast and fully recoverable. It can be proposed that this sensing material deposited onto gold coated glass substrates has a good sensitivity and selectivity for chloroform vapor. This material may also find potential applications in the development of room temperature organic vapor sensing devices. (C) 2011 Elsevier B.V. All rights reserved.Öğe p-phthalimidobenzoic thin film for volatile organic vapor detection(Natl Inst Optoelectronics, 2010) Sen, S.; Capan, R.; Ozel, M. E.; Hassan, A. K.; Namli, H.; Turhan, O.Thin films of the molecule of p-phthalimidobenzoic acid (FIBA) have been deposited by spin coating and are studied for application as sensing membrane for the detection of alcohols. Atomic force microscopy (AFM) and surface plasmon resosnance (SPR) were used for the characterisation of the FIBA films. Alcohol sensing properties of the obtained films were examined using SPR measurements. AFM images show that FIBA films have the large surface roughness with an estimated roughness RMS value of 6.3 nm. Films with such compact and granular morphology are believed to provide improved sensitivity when used in sensor applications. The measured SPR curves were analysed by applying a least square fitting procedure using Fresnel's reflection theory. FIBA film used as a sensing element for the detection of saturated 2-propanol, ethanol and methanol vapors. Fast response and recovery for all studied analytes have been obtained. These results show that thin films made with this FIBA molecule are demonstrating good suitability for room temperature vapor application.Öğe Phthalimide thin film for methanol vapor detection(Amer Scientific Publishers, 2008) Sen, S.; Capan, R.; Ozel, M. E.; Hassan, A. K.; Turhan, O.; Namli, H.The thin film and sensing properties of a novel (N-phthalimido)-p-aminobenzoic acid (FIABA) compound against methanol vapor is investigated using Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR). AFM results indicated that FIABA molecule is a suitable material to produce thin films by spin coating method, with compact and granular morphology. SPR results showed that thin films of this material are highly selective for methanol vapor with fast response and recovery times. Vapor exposure tests using SPR measurements clearly show that the novel FIABA molecules demonstrate a promising material in the development of room temperature vapor sensing application.Öğe Thin film characterization of novel phthalimide materials(Natl Inst Optoelectronics, 2011) Sen, S.; Capan, R.; Ozel, M. E.; Hassan, A. K.; Turhan, O.; Namli, H.Spin coating technique is employed to produce thin phthalimide films using novel p-phthalimidobenzoic acid (FIBA) and N-(phthalimido)-p-aminobenzoic acid (FIABA) materials. Several spin speeds and various solution concentrations are chosen to monitor the thin film deposition process of these new materials. The optical properties are studied using UV-visible spectroscopy and spectroscopic ellipsometry methods. The absorption of the FIBA and FIABA films against the spin speed showed an exponential behavior. pi -> pi* transition is occurred. The thicknesses of thin films at 2000 rpm are obtained 15.86 nm for FIBA and 12.99 nm for FIABA using spectroscopic ellipsometry results.
