The Experts below are selected from a list of 2217 Experts worldwide ranked by ideXlab platform

S.s. Major - One of the best experts on this subject based on the ideXlab platform.

  • Enhanced photoluminescence of CdS nanocrystallites in LB multilayers on aqueous treatment
    'Elsevier BV', 2011
    Co-Authors: Pavan K. Narayanam, S.s. Talwar, Rs Srinivasa, S.s. Major
    Abstract:

    CdS nanocrystallites were formed within the LB matrix of cadmium arachidate-Arachidic Acid composite multilayer by post deposition H(2)S exposure of precursor cadmium arachidate multilayer. The CdS containing multilayers were subjected to post deposition heat treatment in air in the temperature range of 100-300 degrees C. either directly after the sulphidation process or after being introduced into an aqueous bath. FT-IR spectroscopy was used to study the chemical changes in composite multilayers at different stages of processing. Optical properties of the CdS nanocrystallites were studied by UV-VIS absorption and photoluminescence measurements. A strong enhancement of excitonic emission and suppression of surface states emission from CdS nanocrystallites was observed after heat treatment at 100-150 degrees C in the case of aqueous treated composite multilayer. X ray reflection and atomic force microscopy show that the aqueous treatment results in expulsion of Arachidic Acid to the surface of the multilayer resulting in its facile removal during heat treatment. These results suggest that the response to heat treatment of the composite multilayer containing CdS nanocrystallites depends critically on the proximity and access of the unreacted cadmium arachidate to CdS nanocrystallites. This in turn, provides Cd ions for the passivation of Cd vacancies on the surface of nanocrystallites resulting in a strong enhancement of excitonic emission. Heat treatment at higher temperatures results in drastic reduction of photoluminescence, due to particle growth as well as removal of organic moieties. (C) 2011 Elsevier B.V. All rights reserved

  • cds zns core shell nanoparticles in Arachidic Acid lb films
    Applied Surface Science, 2008
    Co-Authors: P Mandal, Raman S. Srinivasa, S.s. Talwar, S.s. Major
    Abstract:

    Abstract Core–shell CdS/ZnS nanoparticles in Arachidic Acid film were prepared through a novel Langmuir–Blodgett (LB) approach. Post-deposition treatment of the precursor LB multilayers of cadmium arachidate with H 2 S gas followed by intercalation of Zn 2+ ions and further sulfidation result in the formation of CdS/ZnS nanoparticles in the LB film. The formation of these nanoparticles and resulting changes in layered structures were studied by FTIR and X-ray reflection measurements. The optical properties were studied using UV–vis absorption and photoluminescence spectroscopy. A red-shift in the absorption spectrum and enhancement of CdS excitonic emission together with reduction of surface states emission suggest that after the intercalation step, a thin layer of ZnS surrounds the CdS nanoparticles, thus forming a core–shell structure. Subsequent to the second sulfidation, a further red-shift in absorption suggests the formation of a thicker ZnS coating on CdS. Electron diffraction of CdS nanoparticles coated with thicker ZnS showed the diffraction patterns of only ZnS, as expected for core–shell structures.

  • CdS/ZnS core–shell nanoparticles in Arachidic Acid LB films
    'Elsevier BV', 2008
    Co-Authors: Mandal P, S.s. Talwar, Rs Srinivasa, S.s. Major
    Abstract:

    Core–shell CdS/ZnS nanoparticles in Arachidic Acid film were prepared through a novel Langmuir–Blodgett (LB) approach. Post-deposition treatment of the precursor LB multilayers of cadmium arachidate with H2S gas followed by intercalation of Zn2+ ions and further sulfidation result in the formation of CdS/ZnS nanoparticles in the LB film. The formation of these nanoparticles and resulting changes in layered structures were studied by FTIR and X-ray reflection measurements. The optical properties were studied using UV–vis absorption and photoluminescence spectroscopy. A red-shift in the absorption spectrum and enhancement of CdS excitonic emission together with reduction of surface states emission suggest that after the intercalation step, a thin layer of ZnS surrounds the CdS nanoparticles, thus forming a core–shell structure. Subsequent to the second sulfidation, a further red-shift in absorption suggests the formation of a thicker ZnS coating on CdS. Electron diffraction of CdS nanoparticles coated with thicker ZnS showed the diffraction patterns of only ZnS, as expected for core–shell structures.© Elsevie

  • zno nanocrystallites obtained by oxidation of zinc arachidate Arachidic Acid composite multilayers
    Physica Status Solidi (a), 2007
    Co-Authors: Sukhvinder Singh, Raman S. Srinivasa, S.s. Talwar, S.s. Major
    Abstract:

    ZnO nanocrystallites were prepared by the oxidation of Zinc Arachidate-Arachidic Acid (ZnA-AA) composite multilayers grown on quartz and freshly cleaved mica substrates. Control of zinc content in the multilayers was achieved by the manipulation of the subphase pH and the variation in the number of monolayers transferred. FTIR studies of multilayers show a gradual decrease in ZnA content as the subphase pH is reduced. X-ray reflection studies show the presence of a single layered structure in all the asdeposited multilayers transferred at different subphase pH. These observations suggest molecular level mixing of ZnA and Arachidic Acid molecules. The precursor multilayers were oxidized in the temperature range of 100-700 °C. The formation of ZnO is confirmed by UV-Visible spectroscopy. Atomic force micrographs show that the oxidation treatment resulted in either large agglomerates of ZnO nanocrystallites or isolated nanocrystallites, depending on the zinc content of the precursor multilayers. Typically, 7 monolayers ZnA-AA transferred at subphase pH of 5.0 on mica and oxidized at 700 °C resulted in uniformly distributed, isolated and nearly mono-dispersed nanocrystallites of size 11 ± 3 nm.

  • ZnO and Zn1-xCdxO nanocrystallites obtained by oxidation of precursor Langmuir-Blodgett multilayers
    'Elsevier BV', 2007
    Co-Authors: Singh Sukhvinder, S.s. Talwar, Rs Srinivasa, S.s. Major
    Abstract:

    ZnO and Zn1−xCdxO nanocrystallites were prepared by oxidation of zinc arachidate–Arachidic Acid and zinc arachidate–cadmium arachidate–Arachidic Acid LB multilayers, respectively. The metal content of the multilayers was controlled by manipulation of subphase composition and pH. Precursor multilayers were oxidized in the temperature range of 400 °C–700 °C. The formation of ZnO and Zn1−xCdxO was confirmed by UV–Visible spectroscopy. Uniformly distributed, isolated and nearly mono-dispersed nanocrystallites of ZnO (11 ± 3 nm) and Zn1−xCdxO (18 ± 6 nm) were obtained.© Elsevie

S.s. Talwar - One of the best experts on this subject based on the ideXlab platform.

  • Enhanced photoluminescence of CdS nanocrystallites in LB multilayers on aqueous treatment
    'Elsevier BV', 2011
    Co-Authors: Pavan K. Narayanam, S.s. Talwar, Rs Srinivasa, S.s. Major
    Abstract:

    CdS nanocrystallites were formed within the LB matrix of cadmium arachidate-Arachidic Acid composite multilayer by post deposition H(2)S exposure of precursor cadmium arachidate multilayer. The CdS containing multilayers were subjected to post deposition heat treatment in air in the temperature range of 100-300 degrees C. either directly after the sulphidation process or after being introduced into an aqueous bath. FT-IR spectroscopy was used to study the chemical changes in composite multilayers at different stages of processing. Optical properties of the CdS nanocrystallites were studied by UV-VIS absorption and photoluminescence measurements. A strong enhancement of excitonic emission and suppression of surface states emission from CdS nanocrystallites was observed after heat treatment at 100-150 degrees C in the case of aqueous treated composite multilayer. X ray reflection and atomic force microscopy show that the aqueous treatment results in expulsion of Arachidic Acid to the surface of the multilayer resulting in its facile removal during heat treatment. These results suggest that the response to heat treatment of the composite multilayer containing CdS nanocrystallites depends critically on the proximity and access of the unreacted cadmium arachidate to CdS nanocrystallites. This in turn, provides Cd ions for the passivation of Cd vacancies on the surface of nanocrystallites resulting in a strong enhancement of excitonic emission. Heat treatment at higher temperatures results in drastic reduction of photoluminescence, due to particle growth as well as removal of organic moieties. (C) 2011 Elsevier B.V. All rights reserved

  • cds zns core shell nanoparticles in Arachidic Acid lb films
    Applied Surface Science, 2008
    Co-Authors: P Mandal, Raman S. Srinivasa, S.s. Talwar, S.s. Major
    Abstract:

    Abstract Core–shell CdS/ZnS nanoparticles in Arachidic Acid film were prepared through a novel Langmuir–Blodgett (LB) approach. Post-deposition treatment of the precursor LB multilayers of cadmium arachidate with H 2 S gas followed by intercalation of Zn 2+ ions and further sulfidation result in the formation of CdS/ZnS nanoparticles in the LB film. The formation of these nanoparticles and resulting changes in layered structures were studied by FTIR and X-ray reflection measurements. The optical properties were studied using UV–vis absorption and photoluminescence spectroscopy. A red-shift in the absorption spectrum and enhancement of CdS excitonic emission together with reduction of surface states emission suggest that after the intercalation step, a thin layer of ZnS surrounds the CdS nanoparticles, thus forming a core–shell structure. Subsequent to the second sulfidation, a further red-shift in absorption suggests the formation of a thicker ZnS coating on CdS. Electron diffraction of CdS nanoparticles coated with thicker ZnS showed the diffraction patterns of only ZnS, as expected for core–shell structures.

  • CdS/ZnS core–shell nanoparticles in Arachidic Acid LB films
    'Elsevier BV', 2008
    Co-Authors: Mandal P, S.s. Talwar, Rs Srinivasa, S.s. Major
    Abstract:

    Core–shell CdS/ZnS nanoparticles in Arachidic Acid film were prepared through a novel Langmuir–Blodgett (LB) approach. Post-deposition treatment of the precursor LB multilayers of cadmium arachidate with H2S gas followed by intercalation of Zn2+ ions and further sulfidation result in the formation of CdS/ZnS nanoparticles in the LB film. The formation of these nanoparticles and resulting changes in layered structures were studied by FTIR and X-ray reflection measurements. The optical properties were studied using UV–vis absorption and photoluminescence spectroscopy. A red-shift in the absorption spectrum and enhancement of CdS excitonic emission together with reduction of surface states emission suggest that after the intercalation step, a thin layer of ZnS surrounds the CdS nanoparticles, thus forming a core–shell structure. Subsequent to the second sulfidation, a further red-shift in absorption suggests the formation of a thicker ZnS coating on CdS. Electron diffraction of CdS nanoparticles coated with thicker ZnS showed the diffraction patterns of only ZnS, as expected for core–shell structures.© Elsevie

  • zno nanocrystallites obtained by oxidation of zinc arachidate Arachidic Acid composite multilayers
    Physica Status Solidi (a), 2007
    Co-Authors: Sukhvinder Singh, Raman S. Srinivasa, S.s. Talwar, S.s. Major
    Abstract:

    ZnO nanocrystallites were prepared by the oxidation of Zinc Arachidate-Arachidic Acid (ZnA-AA) composite multilayers grown on quartz and freshly cleaved mica substrates. Control of zinc content in the multilayers was achieved by the manipulation of the subphase pH and the variation in the number of monolayers transferred. FTIR studies of multilayers show a gradual decrease in ZnA content as the subphase pH is reduced. X-ray reflection studies show the presence of a single layered structure in all the asdeposited multilayers transferred at different subphase pH. These observations suggest molecular level mixing of ZnA and Arachidic Acid molecules. The precursor multilayers were oxidized in the temperature range of 100-700 °C. The formation of ZnO is confirmed by UV-Visible spectroscopy. Atomic force micrographs show that the oxidation treatment resulted in either large agglomerates of ZnO nanocrystallites or isolated nanocrystallites, depending on the zinc content of the precursor multilayers. Typically, 7 monolayers ZnA-AA transferred at subphase pH of 5.0 on mica and oxidized at 700 °C resulted in uniformly distributed, isolated and nearly mono-dispersed nanocrystallites of size 11 ± 3 nm.

  • ZnO and Zn1-xCdxO nanocrystallites obtained by oxidation of precursor Langmuir-Blodgett multilayers
    'Elsevier BV', 2007
    Co-Authors: Singh Sukhvinder, S.s. Talwar, Rs Srinivasa, S.s. Major
    Abstract:

    ZnO and Zn1−xCdxO nanocrystallites were prepared by oxidation of zinc arachidate–Arachidic Acid and zinc arachidate–cadmium arachidate–Arachidic Acid LB multilayers, respectively. The metal content of the multilayers was controlled by manipulation of subphase composition and pH. Precursor multilayers were oxidized in the temperature range of 400 °C–700 °C. The formation of ZnO and Zn1−xCdxO was confirmed by UV–Visible spectroscopy. Uniformly distributed, isolated and nearly mono-dispersed nanocrystallites of ZnO (11 ± 3 nm) and Zn1−xCdxO (18 ± 6 nm) were obtained.© Elsevie

Yukihiro Ozaki - One of the best experts on this subject based on the ideXlab platform.

  • structural characterization of a mixed langmuir blodgett film of a merocyanine dye derivative deuterated Arachidic Acid binary system and the influence of successive hydrothermal treatment in the liquid phase on the film as investigated by polarized
    Journal of Physical Chemistry B, 2010
    Co-Authors: Yoshiaki Hirano, Ari Maio, Yasutaka Kitahama, Asuka Yamazaki, Yukihiro Ozaki
    Abstract:

    We have investigated the structure of the mixed Langmuir−Blodgett (LB) film of a merocyanine dye derivative (MO18)−deuterated Arachidic Acid (C20-d) binary system and the influence of successive hydrothermal treatment in the liquid phase (HTTL) on the mixed LB film by means of polarized UV−visible and IR absorption spectroscopy. The visible absorption band with in-plane anisotropy at 503 nm before HTTL transforms into an absorption band with in-plane isotropy at 557 nm after HTTL for 16−18 min through a peak maximum near 520 nm after HTTL for 2−12 min. The degree of total MO18 intramolecular charge transfer for the 503 nm band is the largest among those for all of the bands. Therefore, the 503 nm band is ascribed to the MO18 H-like aggregation, based on its shape, peak height, and in-plane anisotropy, the subsequent change to two kinds of visible peaks by successive HTTL, and the most degree of MO18 intramolecular charge transfer among all of the aggregation states. While the MO18 hydrocarbon chain takes ...

  • influence of heat treatment in air and subsequent hydrothermal treatment in the liquid phase or water treatment in the liquid phase on a mixed langmuir blodgett film of merocyanine dye Arachidic Acid n octadecane ternary system
    Journal of Molecular Structure, 2010
    Co-Authors: Yoshiaki Hirano, Ari Maio, Akira Fukuda, Yasutaka Kitahama, Yukihiro Ozaki
    Abstract:

    Abstract We have investigated the influence of heat treatment in air (HT), and subsequent hydrothermal treatment in the liquid phase (HTTL) or water treatment in the liquid phase (WTL) on the H-aggregate of mixed Langmuir–Blodgett (LB) films of merocyanine dye (MS 18 )-Arachidic Acid (C 20 )- n -octadecane (AL 18 ) ternary system by means of polarized visible and IR absorption spectroscopy. The MS 18 monomer is obtained from the first application of HT to the H-aggregate, and the monomer rapidly changes into the J-aggregate upon subsequent HTTL. This demonstrates variation via the monomer for reorganization of the MS 18 chromophore from H- to J-aggregates induced by directly performing HTTL to the H-aggregate in our previous study. While the number of gauche conformers in the MS 18 hydrocarbon chain increases by initial HT, the hydrocarbon chain adopts an all- trans conformation after subsequent HTTL. In addition, the degree of orientation of the MS 18 hydrocarbon chain after HT also approximates to that before HT. The C 20 hexagonal packing after HT turns to orthorhombic one with subsequent HTTL, and the orientation disorder of C 20 hydrocarbon chain caused by HT is renovated as well. The structural changes in the MS 18 and C 20 hydrocarbon chains resulting from latter HTTL arise from the hydrophobic effect in the presence of warm water. Moreover, it has been verified that the AL 18 evaporation strongly relates to the dissociation of H-aggregate, but is not responsible for the variation from the monomer to J-aggregate. Comparing the results obtained upon application of HT/HTTL and HT/WTL, it has been concluded that both large relative permittivity and thermal energy inherent in warm water are quite essential in inducing the rapid reconstitution of MS 18 aggregation state from the monomer to J-aggregate. These also promote the restoration of conformation and orientation changes in the MS 18 hydrocarbon chain, and the modification of subcell packing and orientation disorder in the C 20 hydrocarbon chain.

  • thermal behavior of h aggregate in a mixed langmuir blodgett film of merocyanine dye Arachidic Acid and n octadecane ternary system investigated by uv visible and ir absorption spectroscopy
    Journal of Physical Chemistry B, 2008
    Co-Authors: Yoshiaki Hirano, Shinsuke Tateno, Yoshihide Yamashita, Yukihiro Ozaki
    Abstract:

    We have investigated the thermal behavior of H-aggregate in a mixed Langmuir−Blodgett (LB) film of the merocyanine dye (MS18)-Arachidic Acid (C20)-n-octadecane (AL18) ternary system by means of UV−visible and IR absorption spectroscopy in the range from 25 to 250 °C with a continuous scan. The results of both UV−visible and IR spectra indicate that the temperature-dependent variation in MS18 aggregation state is linked not only with the degree of intramolecular charge transfer and the behavior of packing, orientation, conformation, and thermal mobility of the MS18 hydrocarbon chain but also with the presence and absence of AL18. The H-aggregate dissociates from 25 up to 50 °C, which is caused by the AL18 evaporation from the mixed LB film and the increment of thermal mobility of the MS18 hydrocarbon chain. From 110 to 160 °C, blue-shifted bands, attributed to the oligomeric MS18 aggregation, appear near 515 nm in the MS18-C20-AL18 ternary system as well. The temperature at which the 515 nm band occurs is ...

  • conversion of the aggregation state of merocyanine dye modification of the subcell packing of Arachidic Acid and removal of the majority of n octadecane by hydrothermal treatment in the liquid phase in a mixed langmuir blodgett film of the ternary sy
    Langmuir, 2008
    Co-Authors: Yoshiaki Hirano, And Ari Maio, Yukihiro Ozaki
    Abstract:

    We have investigated the influence of heat treatment in an air atmosphere (HT) and hydrothermal treatment in the liquid phase (HTTL) on the H-aggregate in a mixed Langmuir−Blodgett (LB) film of merocyanine dye with an octadecyl group (MS18)−Arachidic Acid (C20)−n-octadecane (AL18) ternary system by means of polarized visible and IR absorption spectroscopy. HT causes the variation from the H-aggregate to the monomer, the increment in the number of gauche conformers in the MS18 hydrocarbon chain, the slight orientation change in the C20 hydrocarbon chain, and the complete evaporation of AL18. The dissociation of MS18 is probably ascribed to the complete evaporation of AL18 from the mixed LB film and the increase in thermal mobility of the long axis of the MS18 hydrocarbon chain during HT. However, HTTL can easily and rapidly induce the conversion of the MS18 aggregation state from H- to J-aggregates, the modification of the C20 subcell packing from hexagonal to orthorhombic, and the removal of most of the A...

  • thermal behavior of j aggregates in mixed langmuir blodgett films composed of merocyanine dye and deuterated Arachidic Acid investigated by uv visible and infrared absorption spectroscopy
    Langmuir, 2007
    Co-Authors: Yoshiaki Hirano, Shinsuke Tateno, Yukihiro Ozaki
    Abstract:

    We have investigated the thermal behavior of J-aggregates in the mixed Langmuir−Blodgett (LB) films composed of the merocyanine dye (MS18)-deuterated Arachidic Acid (C20-d) binary system in the temperature range from 25 to 250 °C by means of UV−visible and IR transmission absorption spectroscopy. The temperature-dependent variations in both UV−visible and IR absorption spectra indicate that the MS18 aggregation states are linked with the MS18 intramolecular charge transfer and the behavior of the packing, orientation, conformation, and thermal mobility of the MS18 hydrocarbon chain. The J-aggregate formed at 25 °C in the mixed LB films dissociates in the temperature range from 25 to 110 °C, which is mainly ascribed to the increase in the thermal mobility of MS18 hydrocarbon chain and the dissociation of the chelation by a cadmium ion to the MS18 keto group. A thermally induced blue-shifted band appears at around 515 nm from 110 to 160 °C. This band is attributed to oligomeric aggregation with side-by-side...

Sigrid Bernstorff - One of the best experts on this subject based on the ideXlab platform.

  • Structure of CdS–Arachidic Acid composite LB multilayers
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2002
    Co-Authors: N. Prasanth Kumar, S.s. Talwar, S.s. Major, S.n Narang, Pavo Dubček, Satish Vitta, Heinz Amenitsch, Sigrid Bernstorff
    Abstract:

    Abstract Langmuir–Blodgett (LB) multilayers of cadmium arachidate were used as precursors to grow semiconducting CdS nanoclusters. The formation of CdS in the multilayers was determined by Fourier transform-infrared (FT-IR), ultraviolet–visible (UV–vis) and Raman spectroscopy. The structural changes occurring as a consequence of CdS formation have been characterized using X-ray reflection (XR) and grazing incidence X-ray diffraction (GIXD) techniques. The CdS containing composite multilayers exhibit the presence of two types of molecular domains, one with close packed herringbone arrangement and the other with tilted molecular chains with no in-plane order. The structural and spectroscopic evidences together suggest that the CdS nanoclusters formed within the Arachidic Acid LB matrix are quasi two-dimensional in nature with lateral dimension ∼5–10 nm and thickness ∼1.1 nm.

  • structure of cds Arachidic Acid composite lb multilayers
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2002
    Co-Authors: Prasanth N Kumar, S.s. Talwar, S.s. Major, S.n Narang, Pavo Dubček, Satish Vitta, Heinz Amenitsch, Sigrid Bernstorff
    Abstract:

    Abstract Langmuir–Blodgett (LB) multilayers of cadmium arachidate were used as precursors to grow semiconducting CdS nanoclusters. The formation of CdS in the multilayers was determined by Fourier transform-infrared (FT-IR), ultraviolet–visible (UV–vis) and Raman spectroscopy. The structural changes occurring as a consequence of CdS formation have been characterized using X-ray reflection (XR) and grazing incidence X-ray diffraction (GIXD) techniques. The CdS containing composite multilayers exhibit the presence of two types of molecular domains, one with close packed herringbone arrangement and the other with tilted molecular chains with no in-plane order. The structural and spectroscopic evidences together suggest that the CdS nanoclusters formed within the Arachidic Acid LB matrix are quasi two-dimensional in nature with lateral dimension ∼5–10 nm and thickness ∼1.1 nm.

Raman S. Srinivasa - One of the best experts on this subject based on the ideXlab platform.

  • cds zns core shell nanoparticles in Arachidic Acid lb films
    Applied Surface Science, 2008
    Co-Authors: P Mandal, Raman S. Srinivasa, S.s. Talwar, S.s. Major
    Abstract:

    Abstract Core–shell CdS/ZnS nanoparticles in Arachidic Acid film were prepared through a novel Langmuir–Blodgett (LB) approach. Post-deposition treatment of the precursor LB multilayers of cadmium arachidate with H 2 S gas followed by intercalation of Zn 2+ ions and further sulfidation result in the formation of CdS/ZnS nanoparticles in the LB film. The formation of these nanoparticles and resulting changes in layered structures were studied by FTIR and X-ray reflection measurements. The optical properties were studied using UV–vis absorption and photoluminescence spectroscopy. A red-shift in the absorption spectrum and enhancement of CdS excitonic emission together with reduction of surface states emission suggest that after the intercalation step, a thin layer of ZnS surrounds the CdS nanoparticles, thus forming a core–shell structure. Subsequent to the second sulfidation, a further red-shift in absorption suggests the formation of a thicker ZnS coating on CdS. Electron diffraction of CdS nanoparticles coated with thicker ZnS showed the diffraction patterns of only ZnS, as expected for core–shell structures.

  • zno nanocrystallites obtained by oxidation of zinc arachidate Arachidic Acid composite multilayers
    Physica Status Solidi (a), 2007
    Co-Authors: Sukhvinder Singh, Raman S. Srinivasa, S.s. Talwar, S.s. Major
    Abstract:

    ZnO nanocrystallites were prepared by the oxidation of Zinc Arachidate-Arachidic Acid (ZnA-AA) composite multilayers grown on quartz and freshly cleaved mica substrates. Control of zinc content in the multilayers was achieved by the manipulation of the subphase pH and the variation in the number of monolayers transferred. FTIR studies of multilayers show a gradual decrease in ZnA content as the subphase pH is reduced. X-ray reflection studies show the presence of a single layered structure in all the asdeposited multilayers transferred at different subphase pH. These observations suggest molecular level mixing of ZnA and Arachidic Acid molecules. The precursor multilayers were oxidized in the temperature range of 100-700 °C. The formation of ZnO is confirmed by UV-Visible spectroscopy. Atomic force micrographs show that the oxidation treatment resulted in either large agglomerates of ZnO nanocrystallites or isolated nanocrystallites, depending on the zinc content of the precursor multilayers. Typically, 7 monolayers ZnA-AA transferred at subphase pH of 5.0 on mica and oxidized at 700 °C resulted in uniformly distributed, isolated and nearly mono-dispersed nanocrystallites of size 11 ± 3 nm.

  • cdxzn1 xs Arachidic Acid composite lb films
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2005
    Co-Authors: Marzieh Parhizkar, Nigvendra Kumar, Pradipta K. Nayak, S.s. Talwar, S.s. Major, Raman S. Srinivasa
    Abstract:

    Abstract Mixed LB multilayers of cadmium arachidate–zinc arachidate (CdA–ZnA) have been exposed to H 2 S to form Cd x Zn 1− x S alloy nanoclusters within the multilayers. FTIR and UV–vis spectra of H 2 S exposed multilayers showed that the conversion of arachidate salt into Arachidic Acid (AA) and sulphide formation begins in the first 5 min and is completed in ∼3 h of H 2 S exposure. X-ray reflection studies and the nature of CH 2 scissoring band of the composite multilayers show that the formation of sulphide nanoclusters is accompanied by the formation of molecular chain domains with different polymorphic phases of AA, depending upon the relative proportions of CdA and ZnA in the precursor multilayer. Depending upon the CdS and ZnS content, the absorption edge is found to continuously shift from that of pure CdS to that of pure ZnS nanoclusters, indicating the formation of Cd x Zn 1− x S alloy nanoclusters in the Arachidic Acid matrix. The nanocluster formation is more facile in the mixed archidate multilayers than in pure CdA or ZnA multilayers.