共查询到20条相似文献,搜索用时 15 毫秒
1.
I.L. Bolotin 《Applied Surface Science》2006,252(19):6533-6536
A quartz crystal microbalance (QCM) has been used to determine total-mass sputtering yields of PMMA films by 1-16 keV C60+,2+ ion beams. Quantitative sputtering yields for PMMA are presented as mass loss per incident ion Ym. Mass-lost rate QCM data show that a 13 keV C60 cluster leads to emission equivalent to 800 PMMA molecules per ion. The power law obtained for the increase in sputtering yield with primary ion energy is in good agreement those predicted by “thermal spike” regime and MD models, when crater sizes are used to estimate sputtering. 相似文献
2.
Molecular dynamics simulations of the 20-keV C60 bombardment at normal incidence of Si, SiC, diamond and graphite targets were performed. The unique feature of these targets is that strong covalent bonds can be formed between carbon atoms from the C60 projectile and atoms in the solid material. The mesoscale energy deposition footprint (MEDF) model is used to gain physical insight into how the sputtering yields depend on the substrate characteristics. A large proportion of the carbon atoms from the C60 projectile are implanted into the lattice structure of the target. The sputtering yield from SiC is ∼twice that from either diamond or Si and this can be explained by both the region of the energized cylindrical tract created by the impact and the number density. On graphite, the yield of sputtered atoms is negligible because the open lattice allows the cluster to deposit its energy deep within the solid. The simulations suggest that build up of carbon with a graphite-like structure would reduce any sputtering from a solid with C60+ bombardment. 相似文献
3.
Michael F. Russo Jr. Igor A. Wojciechowski Barbara J. Garrison 《Applied Surface Science》2006,252(19):6423-6425
Molecular dynamics simulations were performed to study the behavior of cluster SIMS. Two predominant cluster ion beam sources, C60 and Au3, were chosen for comparison. An amorphous water ice substrate was bombarded with incident energy of 5 keV. The C60 cluster was observed to shatter upon impact creating a crater of damage approximately 8 nm deep. Although Au3 was also found to both break apart and form a damage crater, it continued along its initial trajectory causing damage roughly 10 nm deep into the sample and becoming completely imbedded. It is suggested that this difference in behavior is due to the large mass of Au relative to the substrate water molecule. 相似文献
4.
In secondary ion mass spectrometry, polyatomic primary ion sources are known to enhance yields from many surfaces including polymers. In order to understand the fundamental causes for these increases, the enhancement as a function of material type and molecular weight needs to be delineated. In this article, we report results from a systematic investigation of polymeric films of polystyrene (PS) with varying molecular weights to examine the influence of the primary ion beam on the secondary ion yields in time of flight secondary ion mass spectrometry (ToF-SIMS). The masses of the polymers investigated ranged from 1000 to 20,000 Da, or from about n = 10 to 200 where n indicates the number of polymeric units in a polymer chain. The polymers had a narrow molecular weight range (PDI < 1.07). The multilayer polymeric films (10-30 nm) characterized by AFM were prepared by spin-casting onto silicon substrates and were analyzed using Au+ and C60+ primary ion beams. The analysis with the two beams provided a useful comparison between atomic and polyatomic primary ion sources. Information gathered from this study provides insight into the role of molecular weight on the observed yield enhancement from polyatomic ion sources. 相似文献
5.
Jeanette Kordys John S. Fletcher Nicholas P. Lockyer John C. Vickerman 《Applied Surface Science》2008,255(4):890-892
Effects of platinum silicon, graphite and PET substrates on the secondary ion yield of sub-monolayer and multilayer samples of Cyclosporin A following 20 keV Au+, Au3+and C60+ impacts have been investigated. The obtained results of sub-monolayer samples show that platinum enhances the yield of the pseudo-molecular ion following Au+ and Au3+ impacts due to the high density of the substrate that enables the energy of the primary ions to be deposited near the surface. C60+ impacts on sub-monolayer samples are less effective, but there is an enhancement on PET substrates. Impacts of 20 keV Au+ and Au3+ are not very efficient on multilayer samples. 20 keV C60+ impacts enhance the yields significantly, especially for the relatively high molecular weight [M+H]+ ion. 相似文献
6.
The secondary ion mass spectrum of silicon sputtered by high energy C60+ ions in sputter equilibrium is found to be dominated by Si clusters and we report the relative yields of Sim+ (1 ≤ m ≤ 15) and various SimCn+ clusters (1 ≤ m ≤ 11 for n = 1; 1 ≤ m ≤ 6 for n = 2; 1 ≤ m ≤ 4 for n = 3). The yields of Sim+ clusters up to Si7+ are significant (between 0.1 and 0.6 of the Si+ yield) with even numbered clusters Si4+ and Si6+ having the highest probability of formation. The abundances of cluster ions between Si8+ and Si11+ are still significant (>1% relative to Si+) but drop by a factor of ∼100 between Si11+ and Si13+. The probability of formation of clusters Si13+-Si15+ is approximately constant at ∼5 × 10−4 relative to Si+ and rising a little for Si15+, but clusters beyond Si15 are not detected (Sim≥16+/Si+ < 1 × 10−4). The probability of formation of Sim+ and SimCn+ clusters depends only very weakly on the C60+ primary ion energy between 13.5 keV and 37.5 keV. The behaviour of Sim+ and SimCn+ cluster ions was also investigated for impacts onto a fresh Si surface to study the effects that saturation of the surface with C60+ in reaching sputter equilibrium may have had on the measured abundances. By comparison, there are very minor amounts of pure Sim+ clusters produced during C60+ sputtering of silica (SiO2) and various silicate minerals. The abundances for clusters heavier than Si2+ are very small compared to the case where Si is the target.The data reported here suggest that Sim+ and SimCn+ cluster abundances may be consistent in a qualitative way with theoretical modelling by others which predicts each carbon atom to bind with 3-4 Si atoms in the sample. This experimental data may now be used to improve theoretical modelling. 相似文献
7.
The damage characteristics of polyethylene terephthalate (PET) have been studied under bombardment by C60+, Au3+ and Au+ primary ions. The observed damage cross-sections for the three ion beams are not dramatically different. The secondary ion yields however were significantly enhanced by the polyatomic primary ions where the secondary ion yield of the [M + H]+ is on average 5× higher for C60+ than Au3+ and 8× higher for Au3+ than Au+. Damage accumulates under Au+ and Au3+ bombardment while C60+ bombardment shows a lack of damage accumulation throughout the depth profile of the PET thick film up to an ion dose of ∼1 × 1015 ions cm−2. These properties of C60+ bombardment suggest that the primary ion will be a useful molecular depth profiling tool. 相似文献
8.
Per Malmberg Heinrich F. Arlinghaus Jan Holmgren Håkan Nygren 《Applied Surface Science》2008,255(4):926-928
In the present study, SF5+ and C60+ were used as primary ions for sputtering and Bi3+ was used as primary ions for analysis. The depth profiling procedure was utilized to make 3D images of the chemistry of single cultured cells and tissue samples of intact intestinal epithelium.The results show sputtering of organic material from cells and tissue with both SF5+ and C60+ sources. Cholesterol fragments were found in the superficial layers when sputtering with C60+. Spectra were collected revealing the change in yield along the z-axis of the sample. 3D images of the localization of Na, K, phosphocholine and cholesterol were constructed with both ion sources for single cell cultures and the mouse intestine.Cryostate sections of mouse intestine were analysed in 2D and the results were compared with the 3D image of the intestine. The localization of cholesterol and phosphocholine was found to be similar in cryostate sections analysed in two dimensions and the sputtered, freeze-dried intestine analysed in 3D. The comparison of 2D and 3D images suggest that the phosphocholine signal faded with C60+ sputtering. In conclusion, both C60+ and SF5+ can be used as primary ion sources for sputtering of organic material from cells and tissues. Consecutive analysis with a Bi3+ source can be used to obtain image stacks that could be used for reconstruction of 3D images. 相似文献
9.
The effect of incident angle on the quality of SIMS molecular depth profiling using C60+ was investigated. Cholesterol films of ∼300 nm thickness on Si were employed as a model and were eroded using 40 keV C60+ at an incident angle of 40° and 73° with respect to the surface normal. The erosion process was characterized by determining at each angle the relative amount of chemical damage, the total sputtering yield of cholesterol molecules, and the interface width between the film and the Si substrate. The results show that there is less molecule damage at an angle of incidence of 73° and that the total sputtering yield is largest at an angle of incidence of 40°. The measurements suggest reduced damage is not necessarily dependent upon enhanced yields and that depositing the incident energy nearer the surface by using glancing angles is most important. The interface width parameter supports this idea by indicating that at the 73° incident angle, C60+ produces a smaller altered layer depth. Overall, the results show that 73° incidence is the better angle for molecular depth profiling using 40 keV C60+. 相似文献
10.
The profile of the energy deposition footprint is controlled during the C60+ erosion of Si surfaces by varying the incident energy and/or incident angle geometry. Sputter yield, surface topography, and chemical composition of the eroded surfaces were characterized using atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS). The experiments show that the 10 keV, 40° incident C60+ erosion of Si results in the formation of a C containing, mound-like structure on the solid surface. We find that the occurrence of this C feature can be avoided by increasing the incident energy of the C60+ projectile or by increasing the incident angle of the C60+ projectile. While both strategies allow for the Si samples to be eroded, the occurrence of topographical roughening limits the usefulness of C60+ in ultra-high resolution semiconductor depth profiling. Moreover, we find that the relative effect of changing the incident angle geometry of the C60+ projectile on the profile of the energy deposition footprint, and thus the sputter yield, changes according to the kinetic energy of the projectile and the material of the bombarded surface, a behavior that is quite different than what is observed for an atomic counterpart. 相似文献
11.
Pristine and Au-covered molecular films have been analyzed by ToF-SIMS (TRIFT™), using 15 keV Ga+ (FEI) and 15 keV C60+ (Ionoptika) primary ion sources. The use of C60+ leads to an enormous yield enhancement for gold clusters, especially when the amount of gold is low (2 nmol/cm2), i.e. a situation of relatively small nanoparticles well separated in space. It also allows us to extend significantly the traditional mass range of static SIMS. Under 15 keV C60+ ion bombardment, a series of clusters up to a mass of about 20,000 Da (Au100−: 19,700 Da) is detected. This large yield increase is attributed to the hydrocarbon matrix (low-atomic mass), because the yield increase observed for thick metallic films (Ag, Au) is much lower. The additional yield enhancement factors provided by the Au metallization procedure for organic ions (MetA-SIMS) have been measured under C60+ bombardment. They reach a factor of 2 for the molecular ion and almost an order of magnitude for Irganox fragments such as C4H9+, C15H23O+ and C16H23O−. 相似文献
12.
Claude Poleunis Emmanuel P. Everaert Patrick Bertrand 《Applied Surface Science》2006,252(19):6761-6764
This study deals with the secondary ion yield improvement induced by using C60+ primary ions instead of Ga+ ones to characterize human hair surfaces by ToF-SIMS. For that purpose, a bunch of hair fibres has been analysed with both ion sources. A high improvement is observed for the detection of amino acids with C60+ primary ions as compared to Ga+ ions. As an example, a yield enhancement factor greater than 3000 is found for the CNO− peak. A similar gain is observed for the positive secondary ions characteristic of the amino acids. Most of the atomic ions, such as Ca+, O− and S−, constitute minor peaks with C60+ ions while they often dominate the spectrum in the case of Ga+ ions. However, with the C60+ source, a series of inorganic combination peaks with the elements Ca, S and O are observed in the positive spectra (i.e. HCaSO4+), while they are marginal with the Ga+ source. For the mass range beyond 100 m/z and in both polarities, the hair fingerprints are similar with both sources. In average, for a comparable number of primary ions per spectrum, the C60+ ion source gives intensities between two and three orders of magnitude higher than the Ga+ one. 相似文献
13.
In the present study, the basic issues in C60n+ sputtering are studied using silicon, gold and platinum samples. Sputtering yields are measured for energies in the range of 5-30 keV, by sputtering micrometre sized craters on the surface of flat clean samples and measuring their volumes using atomic force microscopy (AFM). Net deposition of carbon occurs for all three materials at 5 keV, and is not specific to silicon which forms a carbide. The threshold energy for net sputtering is dependent on the sputtering yield and the stopping power of the substrate. Away from the threshold, the sputtering yields agree well with Sigmund and Claussen's thermal spike model after allowance for the sputtering of the deposited carbon atoms. AFM images show the formation of unusual surface topography around the transition region between sputtering and deposition. Analysis of the bottom of a crater using imaging SIMS shows a significant enhancement of carbon clusters as well as various silicon-carbon groups, indicating the importance of carbon deposition and implantation in a gradual mixed layer formed from sputtering. The thickness of this interface layer is shown to be approximately 5 nm. 相似文献
14.
Optical limiting measurements on C60 in toluene-ethylenepropylenediene polymethylene (EPDM) polymer blends and in EPDM polymer films at three different concentrations have been carried out. The measurements were undertaken using 532 nm wavelength, 10 ns pulses from a frequency-doubled Nd-YAG Laser. The results show that the optical limiting efficiency is concentration dependent and that the limiting efficiency for C60 in toluene-EPDM polymer blends is better than in EPDM polymer film samples. 相似文献
15.
In the process of investigating the interaction of fullerene projectiles with adsorbed organic layers, we measured the kinetic energy distributions (KEDs) of fragment and parent ions sputtered from an overlayer of polystyrene (PS) oligomers cast on silver under 15 keV C60+ bombardment. These measurements have been conducted using our TRIFT™ spectrometer, recently equipped with the C60+ source developed by Ionoptika, Ltd. For atomic ions, the intensity corresponding to the high energy tail decreases in the following order: C+(E−0.4) > H+(E−1.5) > Ag+(E−3.5). In particular, the distribution of Ag+ is not broader than those of Ag2+ and Ag3+ clusters, in sharp contrast with 15 keV Ga+ bombardment. On the other hand, molecular ions (fragments and parent-like species) exhibit a significantly wider distribution using C60+ instead of Ga+ as primary ions. For instance, the KED of Ag-cationized PS oligomers resembles that of Ag+ and Agn+ clusters. A specific feature of fullerene projectiles is that they induce the direct desorption of positively charged oligomers, without the need of a cationizing metal atom. The energy spectrum of these PS+ ions is significantly narrower then that of Ag-cationized oligomers. For characteristic fragments of PS, such as C7H7+ and C15H13+ and polycyclic fragments, such as C9H7+ and C14H10+, the high energy decay is steep (E−4 − E−8). In addition, reorganized ions generally show more pronounced high energy tails than characteristic ions, similar to the case of monoatomic ion bombardment. This observation is consistent with the higher excitation energy needed for their formation. Finally, the fraction of hydrocarbon ions formed in the gas phase via unimolecular dissociation of larger species is slightly larger with gallium than with fullerene projectiles. 相似文献
16.
This paper reports that the n-type organic thin-film transistors have been fabricated by using C60 as the active layer and polystyrene as the dielectric.The properties of insulator and the growth characteristic of C60 film were carefully investigated.By choosing different source/drain electrodes,a device with good performance can be obtained.The highest electron field effect mobility about 1.15 cm 2 /(V·s) could reach when Barium was introduced as electrodes.Moreover,the C60 transistor shows a negligible 'hysteresis effect' contributed to the hydroxyl-free of insulator.The result suggests that polymer dielectrics are promising in applications among n-type organic transistors. 相似文献
17.
Fang Zhang 《Journal of luminescence》2010,130(5):787-791
Different C60 aggregates, i.e. nanoparticles, clusters of nanoparticles and microcrystals in room-temperature solutions, are reported to account for the colors of fluorescence emissions centered at 440, 575 and 700 nm, respectively. And the configurations of C60 aggregation created in solutions are revealed to be closely associated with the characteristic interactions between C60 and solvent molecules. On this basis, aggregation behaviors and thus induced optical properties of C60 have been tentatively controlled through adopting solvent mixtures. 相似文献
18.
Hyun Kyong Shon Dahl Hyun Kim Byoung Hoon Lee Dae Won Moon 《Applied Surface Science》2008,255(4):1055-1057
The effects of C60 cluster ion beam bombardment in sputter depth profiling of inorganic-organic hybrid multiple nm thin films were studied. The dependence of SIMS depth profiles on sputter ion species such as 500 eV Cs+, 10 keV C60+, 20 keV C602+ and 30 keV C603+ was investigated to study the effect of cluster ion bombardment on depth resolution, sputtering yield, damage accumulation, and sampling depth. 相似文献
19.
In this letter, dispersion properties of low-frequency electrostatic waves in a C60 molecule are investigated. It is assumed that C60 molecule is charged due to the field emission, and hence the C60 molecule can be regarded as charged dust spheres surrounded by degenerate electrons and ions. We obtain the dispersion relation for the low-frequency electrostatic oscillations in the C60 molecule by using the quantum hydrodynamic model in conjunction with the Poisson equation. 相似文献
20.
在C60单晶超高真空解理面上制备C60的Rb填隙化合物薄膜.用同步辐射光电子能谱研究了相衍变过程.观察到对应于固溶相、Rb1C60和Rb3C60的电子态密度分布.当数纳米厚Rb3C60薄膜在C60单晶(111)解理面形成后,室温条件下进一步沉积Rb至样品表面不产生fcc到bct或bcc结构相变.C60
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同步辐射光电子能谱 相似文献