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Wyświetlanie 1-8 z 8
Tytuł:
Optical Interference Effects in Visible-Near Infrared Spectral Range for Arrays of Vertically Aligned Multiwalled Carbon Nanotubes
Autorzy:
Wąsik, M.
Judek, J.
Świtkowski, K.
Zdrojek, M.
Powiązania:
https://bibliotekanauki.pl/articles/1030331.pdf
Data publikacji:
2017-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ci
78.67.Ch
81.07.De
Opis:
Based on the reflectance spectra for radiation wavelength from about 380 nm to 1.8 μm, the optical interference effects in vertically aligned multiwalled carbon nanotubes films are studied. We performed the measurements for two complementary polarization states of incoming radiation (s- and p-polarization) for nanotubes arrays sparse enough for interference effects to be possible to observe. By performing the measurements for different wavelengths and incidence angles, we mapped the evolution of interference maxima/minima of reflectance signal. The results from this novel approach indicate that for the radiation polarized perpendicularly to tubes axis (s-polarization), the real part of the effective refractive index can be estimated from the classic Fabry-Pérot model. In order to describe the differences between spectra obtained for s- and p-polarizations we discuss the most important factors that affect the reflectance signal in case of investigated nanotubes arrays.
Źródło:
Acta Physica Polonica A; 2017, 131, 2; 232-236
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependences of Optical Energy Gaps of SbSI@CNT and SbSeI@CNT
Autorzy:
Jesionek, M.
Nowak, M.
Kępińska, M.
Bednarczyk, I.
Powiązania:
https://bibliotekanauki.pl/articles/1399102.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Ch
62.23.Hj
78.67.Uh
81.07.Gf
Opis:
This paper presents for the first time temperature dependences of optical energy gaps of SbSI@CNT and SbSeI@CNT, i.e. carbon nanotubes (CNTs) filled with antimony sulfoiodide (SbSI) and antimony selenoiodide (SbSeI). The heterostructures were prepared sonochemically using CNTs and elemental Sb, S or Se and I in the presence of solvent under ultrasonic irradiation. Spectral characteristics of diffusive transmittance and reflectance of SbSI@CNT and SbSeI@CNT were measured in temperature range 274 K < T < 333 K. The determinal temperature dependence of indirect forbidden optical energy gap of SbSI@CNT has been fitted with $E_\text{gIf} (T) = (1.92(2)-3.6(6) \times 10^{-4} \times T) eV$. Indirect allowed optical energy gap of SbSeI@CNT has been fitted with $E_\text{gIa} (T) = (1.817(5)-7.1(2) \times 10^{-4} × T) eV$.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 836-837
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diffraction from $WS_2$ and MoS_2 Nanotubes
Autorzy:
Damnjanović, M.
Vuković, T.
Milošević, I.
Powiązania:
https://bibliotekanauki.pl/articles/1503023.pdf
Data publikacji:
2011-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Km
78.67.Ch
68.37.Yz
Opis:
We present a symmetry based analysis of diffraction intensities of transition metal dichalcogenide nanotubes. Obtained results point out specific features of the intensity distribution that are related to group parameters. It is possible to read out all the group parameters from diffraction patterns, and therefore to characterize nanotube, since symmetry group uniquely determines the chiralty indices.
Źródło:
Acta Physica Polonica A; 2011, 120, 2; 224-226
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Pressure Raman Spectroscopy in Carbon Nanotubes
Autorzy:
Kourouklis, G.
Arvanitidis, J.
Christofilos, D.
Ves, S.
Powiązania:
https://bibliotekanauki.pl/articles/1807795.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Ch
78.30.Na
63.22.-m
62.50.-p
Opis:
This work focuses on the high pressure Raman study of carbon nanostuctures comprising of single- or double-wall carbon nanotubes. The detailed examination of the Raman peaks, especially those attributed to the radial breathing modes of the carbon nanotubes, as a function of pressure provides a wealth of information concerning the pressure response of individual nanotubes as well as the internal-external tube (intratube) interactions. The radial breathing modes of both the internal and the external tubes in double-wall carbon nanotubes show reduced pressure slope values as compared to the corresponding in single-wall carbon nanotubes. The reduced slopes for the internal tubes reflect the pressure screening effect inside the external tubes, while those for the external tubes their structural reinforcement due to the encapsulation of smaller diameter tubes in their interior. Moreover, the magnitude of the pressure screening effect depends strongly on the intratube spacing and thus on the intratube interaction. All the experimental observations are well reproduced qualitatively by means of theoretical calculations based on a simple phenomenological model.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 13-18
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence from β-Irradiated Graphene Layers
Autorzy:
Chruścińska, A.
Przegiętka, K. R.
Szroeder, P.
Oczkowski, H. L.
Rozpłoch, F.
Powiązania:
https://bibliotekanauki.pl/articles/2046889.pdf
Data publikacji:
2006-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.60.Kn
78.60.-b
78.67.Ch
81.05.Uw
Opis:
We found that β-irradiated samples of crystallite graphite and multi-walled carbon nanotubes emit light during heating above room temperature. This behaviour is rather surprising for semimetals. Due to the lack of deep enough energy gap, this optical emission cannot be associated with interband transitions, as it is usually assumed in a thermally stimulated luminescence model. We suppose that the reported accumulated luminescence is the result of thermally stimulated relaxation of some kind of defects created in graphene structures by ionising radiation and therefore we offer to name it the relaxoluminescence. We anticipate the relaxoluminescence to be a starting point for developing a new spectroscopic method for nanotechnology. It can also throw a new light on the nature of defects, which are suspected of being responsible for strange magnetic effects in carbon.
Źródło:
Acta Physica Polonica A; 2006, 110, 1; 71-80
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dispersive Micro Raman Backscattering Spectroscopy Investigation of Arc Discharge Synthesized CNTs Doped by Boron and Nitrogen
Autorzy:
Babanejad, S.
Malekfar, R.
Seyyed Hosseini, S.
Powiązania:
https://bibliotekanauki.pl/articles/1807785.pdf
Data publikacji:
2009-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Fg
63.22.Gh
78.67.Ch
81.07.De
Opis:
Raman scattering studies reveal the remarkable structure and the unusual electronic and phonon properties of carbon nanotubes. In this study, we directly produced boron, B, and nitrogen doped carbon nanotubes by using DC-arc discharge method which normally can be employed for producing carbon nanotubes. We performed experiments without using catalysts and in the presence of Ar gas for producing boron doped carbon nanotubes. At the second and third stages and in the presence of $Al_{2}O_{3}$ and MgO nanopowders as catalysts and nitrogen gas were used for producing nitrogen doped carbon nanotubes. In general, our investigation revealed that some major changes caused by B and N dopants can be observed in the related recorded Raman spectra.
Źródło:
Acta Physica Polonica A; 2009, 116, 2; 217-220
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the hydrogen adsorption to the optical properties of boron nitride nanotubes
Autorzy:
Bayani, A.
Powiązania:
https://bibliotekanauki.pl/articles/1070608.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Ch
85.35.-p
68.43.-h
67.63.Cd
67.80.ff
Opis:
In this research we have studied physisorption of hydrogen molecules on armchair (3,3) boron-nitride nanotube using density functional methods. Optical properties of the boron-nitride nanotube, with and without adsorbed H₂ molecules, were investigated under parallel and perpendicular polarized electric fields. The results indicate that the nanotube optical gap slightly changes due to H₂ physisorption and increasing H₂ physisorption suppresses the boron-nitride nanotube optical spectrum. Also, the nanotube gets more transparent as the H₂ concentration increases, in other words boron-nitride nanotube dielectric function decreases. Anisotropic dielectric function is another result which is determined by random phase approximation method.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 348-351
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Study on Doped Multiwalled Carbon Nanotubes
Autorzy:
Costa, S.
Borowiak-Palen, E.
Powiązania:
https://bibliotekanauki.pl/articles/1807799.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Ch
73.22.-f
81.07.De
61.72.Ww
63.20.-e
Opis:
In the present study we report resonance Raman study on multiwalled carbon nanotubes treated with HCl, $HNO_3$ and $H_2SO_4$. Acids are commonly used in purification procedures in order to remove catalyst particles from the as-produced material. However, it is known that acid treatments in multiwalled carbon nanotubes can induce a surface functionalisation and intercalation of the walls, modifying their electronic properties. Here, we present a comparative study between samples of multiwalled carbon nanotubes modified with the most common acids used in the purification of carbon materials, and the influence of the acid treatment time on their vibronic properties. The samples were analysed via the Raman spectroscopy using the laser length of 785 nm. The presented data reveal the modification of the typical multiwalled carbon nanotubes Raman bands such as: disorder band (D band), the graphite band (G band), and the two-phonon second order Raman band (G' band). The last one shows a broadening effect on its line shape and the appearance of an additional peak. All the treatments enhance the number of defects in the graphitic structure of multiwalled carbon nanotubes.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 32-35
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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