| 1. |
- De Julián Fernández, C., et al.
(författare)
-
Study of the gas optical sensing properties of Au-polyimide nanocomposite films prepared by ion implantation
- 2005
-
Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 111-112:SUPPL., s. 225-229
-
Tidskriftsartikel (refereegranskat)abstract
- Au-polyimide nanocomposites have been synthesized by implanting Au + ions in pyromellitic dianhydride-4,4′ oxydianiline polyimide films prepared by glow discharge vapor deposition polymerisation (GDVDP). A structural and optical characterization shows that Au clusters grow only implanting 5 × 1016 Au+/cm2. This sample class shows interesting dynamic optical absorption sensing responses towards methanol and ethanol vapors in the spectral range corresponding to the surface plasmon resonance (SPR) peak of the gold nanoparticles. Traditional surface plasmon resonance measurements performed onto virgin polyimide thin films in controlled atmosphere show a sensing activity due to a variation of the film thickness and of the real part of refractive index. The comparison of the results obtained onto virgin films and implanted ones suggests that the sensing mechanisms can be attributed both to the modification of polymer optical properties and to the chemical activity of gold nanoparticles. © 2005 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Guidi, V., et al.
(författare)
-
Diffusion-equation approach to describe ionic mobility in nanostructured titania
- 2005
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 72:15
-
Tidskriftsartikel (refereegranskat)abstract
- The linear diffusion equation is proposed to provide a macroscopic description of ionic mobility in nanostructures. This approach has been demonstrated to account for diffusion processes in nanostructured titania-based films. The formulation of a classical diffusion inverse problem and the experimental determination of concentration profiles by Rutherford backscattering spectrometry were used for the purpose. The model has allowed the measurement of the diffusion coefficient of W and Mo impurities in titania. © 2005 The American Physical Society.
|
|
| 3. |
- Baricordi, S., et al.
(författare)
-
Low-energy-channeling surface analysis on silicon crystals designed for high-energy-channeling in accelerators
- 2005
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:9
-
Tidskriftsartikel (refereegranskat)abstract
- Channeling of relativistic particles in bent Si crystals is a powerful technique for use with accelerators. Its efficiency can be found to be highly dependent on the state of the surface of the crystal steering the particles. We investigated the morphology and structure of the surface of the samples that have been used with high efficiency for channeling in accelerators. Low-energy channeling of 2 MeVα particles or protons was used as a probe. We found that mechanical treatment of the samples leads to a superficial damaged layer, which is correlated to efficiency limitations of the crystal in accelerators. In contrast, chemical etching, which was used to treat the surface of the most efficient crystals, leaves a surface with superior perfection. © 2005 American Institute of Physics.
|
|
| 4. |
- Carturan, S., et al.
(författare)
-
Polyimide-based scintillators studied by ion beam induced luminescence
- 2005
-
Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 52:3 II, s. 748-751
-
Tidskriftsartikel (refereegranskat)abstract
- New organic scintillators for ionizing radiation sensors are synthesized by dispersing dye molecules into chemically imidized polyimide hosts in order to obtain detection systems with improved radiation resistance with respect to the traditional polyvinyltoluene-based materials. Nile red (NR) and rhodamine B (RB) are dispersed at different concentrations in polyimides derived from the following monomers: 6FDA-DAD, 6FDA-DAB, and BPDA-3F. Scintillating thin films are produced by the spin coating technique. Scintillation tests are performed both on pure polyimides and on binary systems by means of ion beam induced luminescence (IBIL), in which the emission spectrum is collected during the irradiation of the films with a 4He+ beam. From the intensity and the degradation rate of the IBIL signal during irradiation, the scintillation efficiency with respect to NE102 and the radiation hardness of the produced films are calculated. © 2005 IEEE.
|
|
| 5. |
- Fanchini, G., et al.
(författare)
-
Growth and characterisation of polymeric amorphous carbon and carbon nitride films from propane
- 2005
-
Ingår i: Diamond and related materials. - : Elsevier BV. - 0925-9635 .- 1879-0062. ; 14:3-7, s. 928-933
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we report about the deposition of a-C(N):H films by electron-cyclotron-resonance using propane as a carbon precursor. The films generally present high H contents (up to 61 at.%) and large optical gaps. The maximum N content we obtained is 13 at.%. In nitrogenated films, we observed a strong decrease of the stretching intensity of the infrared spectra of the hydrocarbon (CHn) vibrations, even at very low nitrogen content, the H content being still comparable to that of pure a-C:H. The various phenomena that can lead to such an effect are discussed: (i) different type of hydrogen bonding (CHn and NHn) in presence and in absence of nitrogenation; (ii) weakening of the cross-section of the CHn groups in presence of nitrogen; (iii) large presence of non-bonded hydrogen meaning, with this, either the presence of molecular H2 or unbounded hydrogen. In addition, the residual amount of IR absorption due to C-H vibrations shows that, in a-CN:H, C-H bonded and non-bonded hydrogen does coexist. © 2005 Elsevier B.V. All rights reserved.
|
|
| 6. |
- Vomiero, Alberto, et al.
(författare)
-
The role of N in the resputtering inhibition of Si in W-Si-N reactively sputtered thin layer
- 2005
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 97:3
-
Tidskriftsartikel (refereegranskat)abstract
- W-Si-N thin films were synthesized by reactive sputtering of W 5Si 3 target in an Ar/N 2 mixed atmosphere. The nitrogen atomic concentrations within the films ranged between 0 and 60 at. %, as revealed by Rutherford backscattering measurements. At low nitrogen atom fluxes an intense Si resputtering was observed, leading to the formation of a W-rich layer with respect to target composition. The characterization of plasma parameters during the deposition, carried out with the help of a Langmuir probe, suggests that the Ar neutral atoms reflected by W atoms of the target are the main responsibilities of Si resputtering with respect to charged species, whose resputtering effect is less important. The inhibition of this phenomenon takes place with growing nitrogen concentration. The preferential formation of Si-N bonds with respect to W-N bonds was unveiled by both x-ray photoelectron spectroscopy and Fourier transform infrared absorption spectroscopy. This also justifies the inhibition of Si resputtering. A comparison with literature data concerning W-Si-N systems sputtered at different plasma conditions was performed in order to highlight the influence of plasma parameters on the composition of the layers. © 2005 American Institute of Physics.
|
|
| 7. |
- Della Mea, G., et al.
(författare)
-
14N(α,p)17O nuclear reaction cross-section at 4.9-6.1 MeV
- 2005
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 240:4, s. 803-809
-
Tidskriftsartikel (refereegranskat)abstract
- The 14N(α,p)17O nuclear reaction cross-section was measured in the energy range 4.9-6.1 MeV at the laboratory angle θ = 172° in order to apply ion beam analysis to the detection of N in metal oxynitride layers. Comparison between the new calculation and data in literature was performed, highlighting important discrepancies between the new results and old cross-section data. Application of the new calculations to a standard TiN film suggests improved accuracy for the data in the present work. © 2005 Elsevier B.V. All rights reserved.
|
|
