Helium ion irradiation of polymer films deposited from TMS-Ar plasmas

Polymer films synthesized from plasmas of a tetramethylsilane - Ar mixture were modified by irradiation with 170 keV He ions at fluences ranging from 1 x 10(14) to 1 x 10(16) cm(-2). As revealed by infrared spectroscopy, the ion beam produced intense bond rearrangements, such as the depletion of bonding groups (C-H and Si-H), and induced the formation of new ones, such as O-H and Si-O. From the nanoindentation measurements, a remarkable increase in the surface hardness of the films was observed as the ion fluence was increased. The increases in hardness were accompanied by an increase in the film compaction as shown by using a combination of RBS and film thickness measurements. From both hardness and infrared measurements A was concluded that, under the He ion bombardment, the polymer structure is transformed into a silicon oxycarbide network.

Effects of nitrogen ion irradiation on plasma polymerized films produced from titanium tetraiso pro poxide-oxygen-helium mixtures

In this work films were produced by the plasma enhanced chemical vapor deposition (PECVD) of titanium tetraisopropoxide-oxygen-helium mixtures and irradiated with 150 keV singly-charged nitrogen ions (N(+)) at fluences, phi, between 10(14) and 10(16) cm(-2). Irradiation resulted in compaction, which reached about 40% (measured via the film thickness) at the highest fluence. Infrared reflection-absorption spectroscopy (IRRAS) revealed the presence of Ti-O bonds in all films. Both O-H and C-H groups were present in the as-deposited films, but the density of each of these decreased with increasing phi and was absent at high phi, indicating a loss of hydrogen. X-ray photoelectron spectroscopy (XPS) analyses revealed an increase in the C to Ti atomic ratio as phi increased, while the O to Ti ratio hardly altered, remaining at around 2.8. The optical gap of the films, derived from data obtained by ultraviolet-visible spectroscopy (UVS), remained at about 3.6 eV for all fluences except the highest, for which an abrupt fall to around 1.0 eV was observed. For the irradiated films, the electrical conductivity, measured using the two-point method, showed a systematic increase with increasing phi. (c) 2008 Elsevier B.V. All rights reserved.

Effects of helium ion irradiation on fluorinated plasma polymers

The effects of ion irradiation on fluorinated plasma polymer films are investigated using profilometry, surface contact-angle measurements, infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Remarkably, helium plasma immersion ion implantation (PIII) of several amorphous hydrogenated fluorinated plasma polymers deposited from C(2)H(2)-SF(6), C(6)H(6)-SF(6) or C(6)F(6) produces film compactions of up to 40%, and modifies the surface energy in the 35 to 65 dyn cm(-1) range. As revealed by IRRAS and XPS, the films contain C-H, C-C, C=C, C=O, O-H and C-F groups. XPS spectra confirm the presence of N (typically similar to 5%). The films produced from SF(6)-containing plasmas also contain S. For irradiation times of 80 min, the film carbon content is increased, and the fluorine content is greatly reduced, by factors of about 3 to 15, depending on the initial film composition. (C) 2010 Elsevier B.V. All rights reserved.

Effect of ion irradiation on the structural properties and hardness of a-C:H:Si:O:F films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

XPS investigation of plasma-deposited polysiloxane films irradiated with helium ions

This work describes an XPS investigation of plasma-deposited polysiloxane films irradiated with 170 keV He+ ions at fluences, Phi, ranging from 1 x 10(14) to 1 x 10(16) cm(-2). Modifications in the atomic concentrations of the surface atoms with (D were revealed by changes in the [O]/[Si], [O]/[C] and [C]/[Si] atomic ratios. Surface chemical structure modifications were evidenced by the increasing C1s peak width and asymmetry as Phi was increased, due to the formation of ether and carboxyl functionalities. Moreover, structural transformations were indicated by the positive binding energy shift of the Si2p peaks, due to the increasing Si oxidation. Correlations of the XPS data with other results from previous work on polysiloxanes illustrate the role of ion beam-induced bond breaking on the structural modifications.

Infrared spectroscopy investigation of various plasma-deposited polymer films irradiated with 170 keV He+ ions

This work illustrates the advantages of using p-polarized radiation at an incidence angle of 70 degrees in contrast to the conventional unpolarized beam at normal (or near-normal) incidence for the infrared spectroscopic study of polycarbosilane, polysilazane and polysiloxane thin films synthesized by plasma enhanced chemical vapor deposition (PECVD) and subsequently irradiated with 170 keV He+ ions at fluences from 1 x 10(14) to 1 x 10(16) cm(-2). Several bands not seen using the conventional mode could be observed in the polarized mode. (c) 2006 Elsevier B.V. All rights reserved.

Recalibration of U-doped standard glasses through uranium thin film for neutron-fluence measurements

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Candida albicans inactivation and cell membrane integrity damage by microwave irradiation

In indicating the microwave irradiation for disinfecting dentures it is necessary to see how this procedure influences Candida albicans integrity and viability. The aim of this study was to evaluate the ability of microwaves to inactivate C. albicans and damage cell membrane integrity. Two 200-ml C. albicans (ATCC 10231) suspensions were obtained. A sterile denture was placed in a beaker containing the Experimental (ES) or the Control suspension (CS). ES was microwaved at 650 W for 6 min. Suspensions were optically counted using methylene blue dye uptake as indicative of membrane-damaged cells; spread on Agar Sabouraud dextrose (ASD) for viability assay; or spectrophotometrically measured at 550 nm. Cell-free solutions were submitted to content analyses of protein (Bradford and Pyrogallol red methods); Ca++ (Cresolftaleine complexone method); DNA (spectrophotometer measurements at 260 nm) and K + (selective electrode technique). Data were analysed by Student's t- or Wilcoxon z-tests (α = 0.05). All ES cells demonstrated cell membrane damage. Viable cells were non-existent in the ES ASD plates. No significant difference in optical density between ES and CS was observed (P = 0.272). ES cells released significantly high protein (P < 0.001, Bradford; P = 0.005, Pyrogallol red), K+ (P < 0.001), Ca++ (P = 0.012) and DNA (P = 0.046) contents. Microwaves inactivated C. albicans and damaged cell membrane integrity. © 2007 The Authors.

Annual and monthly mean global, direct and diffuse solar irradiation in Botucatu/SP/Brazil

This paper presents a climatic and statistical analysis of global, direct horizontal and diffuse radiation from a database of solar radiation measured from 1996 to 2006 in the city of Botucatu, SP, Brazil. Variation intervals of hourly and daily irradiation, annual mean 〈H̄G〉, 〈H̄bh〉 and 〈H̄d〉 irradiation, monthly mean 〈H̄G〉, 〈H̄ bh〉 and 〈H̄d〉 irradiation and monthly mean 〈K̄t〉, 〈K̄bh〉 and 〈K̄d〉 fractions were determined. Results showed that values of hourly and daily annual mean irradiation were as follows: 〈H̄G〉=1.49MJ/m2 and 〈H̄ G〉=17.74MJ/m2; 〈H̄bh〉=0. 90MJ/m2 and 〈H̄bh〉=10.33MJ/m2 and 〈H̄d〉=0.57 MJ/m2 and 〈H̄d〉=7.09MJ/m2, respectively. Variation intervals of hourly monthly mean irradiation were as follows: 〈H̄G〉 ranged from 1.65MJ/m2 in March to 1.16MJ/m2 in June; 〈H̄bh〉 ranged from 1.06MJ/m2 in April to 0.79MJ/m2 in June, and 〈H̄d〉 ranged from 0.70MJ/m2 in January to 0.37MJ/m2 in June and July. Similarly, daily 〈H̄ G〉 irradiation ranged from 21.35MJ/m2 in November to 12.94MJ/m2 in June; 〈H̄bh〉 ranged from 11.83MJ/m2 in April to 8.49MJ/m2 in June, and 〈H̄d〉 ranged from 10.29MJ/m2 in December to 4.38MJ/m2 in June. Variation intervals of hourly monthly mean fractions were as follows: 〈K̄t〉 ranged from 43.5% in January to 54.2% in April; 〈K̄bh〉 ranged from 33.6% in January to 58.0% in April and 〈K̄d〉 ranged from 66.4% in January to 42.0% in April. In the same way, daily 〈K̄ t〉 fractions ranged from 45.5% in January to 59.8% in August; 〈K̄bh〉 ranged from 38.9% in January to 62.0% in August and 〈K̄d〉 ranged from 61.1% in January to 37.7% in July.

Silver ion release from electrodes of nanotubes of TiO2 impregnated with Ag nanoparticles applied in photoelectrocatalytic disinfection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)