Molecular adsorption and the chemistry of plasma-deposited thin organic films: Deposition of oligomers of ethylene glycol

Weakly ionized, radio-frequency, glow-discharge plasmas formed from methyl ether or the vapors of a series of dimethyl oligo(ethylene glycol) precursors (general formula: H-(CH₂OCH₂)_n-H;n=1 to 4) were used to deposit organic thin films on polytetrafluoroethylene. X-ray photoelecton spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS) of the thin films were used to infer the importance of adsorption of molecular species from the plasma onto the surface of the growing, organic film during deposition. Films were prepared by plasma deposition of each precursor at similar deposition conditions (i.e., equal plasma power (W), precursor flow rate (F), and deposition duration), and at conditions such that the specific energy (energy/mass) of the discharge (assumed to be constrained byW/FM, whereM=molecular weight of the precursor) was constant. At constantW/FM conditions, two levels of plasma power (and, hence, twoFM levels) and three substrate temperatures were examined. By controlling the energy of the discharge (W/FM) and the substrate temperature, these experiments enabled the study of effects of the size and the vapor pressure of the precursor on the film chemistry. The atomic % of oxygen in the film surface, estimated by XPS, and the intensity of theC-O peak in the XPS C_ls spectra of the films, were used as indicators of the degree of incorporation of precursor moieties into the plasma-deposited films. Analysis of films by SIMS suggested that these two measures obtained from XPS were good indicators of the degree of retention in the deposited films of functional groups from the precursors. The XPS and SIMS data suggest that adsorption of intact precursor molecules or fragments of precursor molecules during deposition can have a significant effect on film chemistry. Plasma deposition of low vapor pressure precursors provides a convenient way of producing thin films with predictable chemistry and a high level of retention of functional groups from the precursor.     

Thermal conversion of poly(paraphenylene–vinylene) precursor films: XPS and ESR studies

The conversion of the precursor into poly(phenylene–vinylene) (PPV) was studied by means of photoelectron spectroscopy (XPS) and electron spin resonance (ESR) on precursor films synthesized from the polymerization of pxylene-tetrahydrophenium halides. The sulfonium precursor containing chlorine or bromine was thermally converted to PPV and analyzed in situ using the spectrometers. It was found by XPS analysis that both halide precursors were thermally converted into polymer in a range of 190–250°C but traces of bromine were still present at >300 °C in the precursor containing Br. Furthermore, a small amount of oxygen in a ketone structure was also present in fully converted films. The ESR results corroborated the XPS experiments, showing a progressive disappearance of the radical distribution related to sulfur sites in a comparable temperature range. A discussion of the conversion process is given in terms of the modification of the core level spectra from XPS and the g distributions from ESR experiments. © 1997 John Wiley & Sons, Ltd.     

Substrate temperature effects on film chemistry in plasma deposition of organics. III. Analysis by static secondary ion mass spectrometry

Static secondary ion mass spectrometry (SIMS) was used to examine the effect of reducing the substrate temperature during the radio frequency plasma deposition of organic films. Studies of two polymerizable plasma precursors (2-hydroxyethyl methacrylate and acrylic acid) and one nonpolymerizable precursor (acetone) deposited without substrate cooling and with liquid nitrogen cooling are presented. Acetone deposited with methanol/dry ice cooling was also investigated. Spectra of polymerizable precursors were analyzed by comparison to spectra for the corresponding conventionally-polymerized polymer films [i.e., poly(hydroxyethyl methacrylate) and poly(acrylic acid)]. Acetone spectra were interpreted by reference to SIMS analysis of plasma-deposited films prepared from isotopically-labelled acetone and to reference homopolymers. Comparison of the SIMS spectra of films deposited at different substrate temperatures indicates that a reduction in substrate temperature generally results in higher intensity of peaks characteristic of oxygenated ion structures. SIMS also suggests that the reduction of substrate temperature results in less polymer unsaturation and fewer structures which form by hydrogen redistribution during the deposition process. These results support the hypothesis that deposition at low substrate temperatures leads to an increase in the proportion of precursor incorporated into the film without substantial fragmentation. Corroborative results from high resolution x-ray photoelectron spectroscopy (XPS) and assays for precursor functional groups by chemical derivatization reactions in conjunction with XPS are also presented. © 1992 John Wiley & Sons, Inc.     

TOF-SIMS and XPS-investigations of ion implanted single crystal 1b-diamonds

Near surface zones of (48)Ti- and (52)Cr-implanted single crystal diamonds (1b-MCD) were characterized by XPS, TOF-SIMS and white light interference microscopy (WLI). By the combination of WLI and TOF-SIMS it was possible to calibrate the depth scale of TOF-SIMS and XPS depth profiles quantitatively. The adjustment of TOF-SIMS and XPS elemental depth profiles in the implantation maximum increases the quantitative detection limit of the implanted elements by more than two orders of magnitude and enables the interpretation of results from wear simulation experiments. Peak fits of XPS C(1s)-photolines indicate the fraction and chemical nature of carbide-like structures in the implantation zone. Qualitative hints on carbide compounds are possibly included in the reconstructed TOF-SIMS spectra but this information can presently only be extracted with the aid of XPS analyses.     

Fluorescence, XPS, and TOF-SIMS surface chemical state image analysis of DNA microarrays

Performance improvements in DNA-modified surfaces required for microarray and biosensor applications rely on improved capabilities to accurately characterize the chemistry and structure of immobilized DNA molecules on micropatterned surfaces. Recent innovations in imaging X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) now permit more detailed studies of micropatterned surfaces. We have exploited the complementary information provided by imaging XPS and imaging TOF-SIMS to detail the chemical composition, spatial distribution, and hybridization efficiency of amine-terminated single-stranded DNA (ssDNA) bound to commercial polyacrylamide-based, amine-reactive microarray slides, immobilized in both macrospot and microarray diagnostic formats. Combinations of XPS imaging and small spot analysis were used to identify micropatterned DNA spots within printed DNA arrays on slide surfaces and quantify DNA elements within individual microarray spots for determination of probe immobilization and hybridization efficiencies. This represents the first report of imaging XPS of DNA immobilization and hybridization efficiencies for arrays fabricated on commercial microarray slides. Imaging TOF-SIMS provided distinct analytical data on the lateral distribution of DNA within single array microspots before and after target hybridization. Principal component analysis (PCA) applied to TOF-SIMS imaging datasets demonstrated that the combination of these two techniques provides information not readily observable in TOF-SIMS images alone, particularly in identifying species associated with array spot nonuniformities (e.g., "halo" or "donut" effects often observed in fluorescence images). Chemically specific spot images were compared to conventional fluorescence scanned images in microarrays to provide new information on spot-to-spot DNA variations that affect current diagnostic reliability, assay variance, and sensitivity.     

Substrate temperature effects on film chemistry in plasma depositions of organics. II. Polymerizable precursors

The influence of substrate temperature during plasma deposition on the chemistry of the organic films formed was examined. Plasma ionization of precursor gases that are polymerizable by conventional mechanisms was studied. Film chemistry was analyzed by x-ray photoelectron spectroscopy (XPS). Monomers that polymerize by a free radical mechanism [2-hydroxyethyl methacrylate (HEMA) and hexafluorobutadiene (HFB)] form more regular polymers (i.e. with less molecular rearrangement) by plasma deposition at low substrate temperatures than monomers that polymerize by ionic mechanisms [ethylene oxide (EO) and tetrahydrofuran (THF)]. In all cases, lowering the substrate temperature during deposition produces films with elemental composition virtually identical to that of the precursor gas. Comparison of high-resolution XPS spectra of the deposited films with those for model polymers suggests that functional groups in the monomers used to generate the plasma are incorporated to a greater extent at low substrate temperatures. The effect of plasma power on the degree of precursor structure retention obtained when reduced substrate temperatures are employed was also examined. Plasma deposition of HEMA at low substrate temperatures and low plasma power produces thin films which are, by core level XPS, indistinguishable from HEMA polymerized by conventional methods. EO and THF films coated at low substrate temperatures on glass, polyethylene, or polytetrafluoroethylene varied widely in surface chemistry due to differences in film uniformity. Film quality (uniformity) is enhanced for these low reactivity precursors by pretreating substrates with an argon plasma. © 1992 John Wiley & Sons, Inc.     

Synthesis,characterization, and thermal properties of novel silicon 1,1,3,3-tetramethylguanidinate derivatives and use as single-source chemical vapor deposition precursors

A series of chemical vapor deposition (CVD) precursors have been synthesized by a single-step reaction of 1,1,3,3-tetramethylguanidine and a variety of silicon chlorides. The structures of the 1,1,3,3-tetramethylguanidinate-based compounds were verified by ¹H NMR, ¹³C NMR, XPS, EI-MS, and elemental analysis. The thermal stability, transport behavior, and vapor pressures of these compounds were evaluated by simultaneous thermal analyses (STA). These compounds are highly stable and those in liquid form are very volatile. Silicon carbonitride (SiCN) thin films were prepared by using bis (tetramethylguanidine)-dimethyl-silane as the precursor in helicon wave plasma chemical vapor deposition (HWP-CVD). The properties of the films were investigated by SEM, AFM, and XPS. The results showed that the films have good uniformities, low friction coefficient, and high hardness, enabling the films for fabrication of semiconductor devices.     

Structural,optical and photoelectron spectroscopic studies of nano/micro ZnO:Cd rods synthesized via sol-gel route

Thin films of cadmium doped zinc oxide rod like microstructure have been synthesized by a very simple sol-gel dip coating technique. Sols were prepared from hydrated zinc oxide precursor and 2-methoxyethanol solvent with monoethanolamine as a sol stabilizer. XRD pattern confirmed the hexagonal wurtzite structure of the deposited ZnO films. Surface morphologies of the films have been studied by a scanning electron microscope and an atomic force microscope, which confirmed that the films are composed of densely packed randomly oriented nano/submicron rods with diameter in the range 300–400 nm having various lengths. We proposed a possible growth mechanism for this rodlike structure. X-ray photoelectron spectroscopic study was used to determine the binding energies and the Zn 2p3/2, Cd 3d5 and O 1s peaks in the XPS spectra were located at 1021.08 eV, 404.6 eV and 529.8 eV respectively, which confirmed the Cd doping in ZnO. Cadmium content in the film was estimated both from energy dispersive X-ray analysis and XPS measurement. Band gap energy determined from optical transmittance spectra systematically varied from 3.28 eV to 3.15 eV for 0% to 5.6% of Cd doping. Urbach parameter determined from the band tail of the transmittance spectra showed that it increased with doping percentage and this parameter for a fixed cadmium doping level decreased with increase of temperature.     

Loss of phosphorous in silica-phosphate sol-gel films

Phosphosilicate films with 90%SiO₂-10%P₂O₅ molar composition, derived from tetraethoxysilane as SiO₂ precursor and triethylphosphate, triethylphosphite or phosphoric acid as P₂O₅ precursors were prepared using the sol-gel method. The films were deposited on glass and ITO coated glass supports. The influence of the type of P₂O₅ precursor, type of substrate and of the thermal treatment (200, 300 and 500°C) on their structure and properties was studied. By spectroellipsometric and XPS measurements the high vaporization of the phosphorous during the densification of the films by thermal treatment was noticed when alkoxide were used, underlying that the mentioned precursors are not recommended for thin phosphosilicate films preparation. The phosphoric acid that forms chemical bond with silica network during the sol-gel process lead to better incorporation of P in the silica network as compared to the P-alkoxides.     

Rapid identification of trimethyl and triethyl amines using sulphonic acidic ionic liquids: A time-of-flight secondary ion mass spectrometry study of fragmentation reactions

The time-of-flight secondary ion mass spectrometry (TOF-SIMS) has emerged as a powerful tool for the unswerving detection of biomolecules, in particular, proteins and peptides. To date, there is very little information available on the direct determination of trimethyl/triethyl amines using TOF-SIMS. One major hurdle in this regard is an ultrahigh vacuum system, usually needed in TOF-SIMS, which hampers its usability to trimethyl/triethyl amines owing to their high evaporation rate. We designed an efficient and sensitive protocol for rapid identification and sensitive determination of tertiaryalkyl amines using TOF-SIMS. The amines were derivatized by reaction with 1,4-butane sultone and sulphuric acid sequentially to afford the corresponding sulphonic acidic ionic liquids (ILs). The TOF-SIMS analysis of these task-specific ILs (TSILs) was carried out in both positive and negative polarity. The positive ion mass spectra of TSILs showed sharp fragmented peaks for tertiaryalkyl amines at typical level and up to 10 ppm. The possible mechanism for different fragmentation pathways in positive polarity was discussed.     

Surface analysis of polyethyleneterephthalate by ESCA and TOF-SIMS

PET (poly(ethylene-terephthalate)) samples provided by different suppliers were investigated with the surface-sensitive methods as electron spectroscopy for chemical analysis (ESCA) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Analysis by means of ESCA provides chemical information from a near-surface region of roughly 6 nm. Specific ESCA data on chemical shifts and on the ratio between oxygen and carbon are compared with corresponding values expected for the molecular structure of bulk PET. In addition, direct chemical information on the molecular structure at the PET surface (essentially from the first two monolayers) has been obtained by TOF-SIMS. Especially, positive and negative TOF-SIMS mass spectra were analyzed in detail and assigned with respect to characteristic polymer fragment ions. Several polymer additives as well as some contaminations present at the PET surfaces could be identified with TOF-SIMS. Dependent on the PET supplier, antioxidants and lubricants such as Irgafos 168, octylstearate, octylpalmitate, octylarachidate and PDMS (polydimethylsiloxane) found at the sample surfaces give typical positive and negative ion fragments.     

Single-crystalline Bi(5)O(7)NO(3) nanofibers: Hydrothermal synthesis, characterization, growth mechanism, and photocatalytic properties

Semifluorinated self-assembled (FAS SA) films fabricated from trifunctional precursors are frequently used in myriad applications, yet an understanding of the effects of fabrication conditions, including deposition time, on adsorption mechanisms and molecular architectures is still being developed. In this work we prepared SA films based on the F(CF(2))(8)(CH(2))(2)SiCl(3) (FAS-17) precursor and characterized these films using a suite of surface analytical techniques. Contact angle, sum frequency generation (SFG) spectroscopy, X-ray photoelectron spectroscopy (XPS), and ellipsometry results are consistent with the formation of disordered sub-monolayer structures at short deposition times, well-ordered monolayers at intermediate deposition times, and inhomogeneous multilayers at long deposition times. Correlation of SFG and XPS results demonstrates a change in FAS-17 chain orientation as the deposition time increases from 2 s to 5 min. Group theory-based calculations, SFG studies, and Fourier-transform infrared (FTIR) results also afford additional evidence in support of the assignment of the SFG signals at ~1345 and ~1370 cm(-1) to the asymmetric stretching mode of the semifluorinated silane chain's terminal CF(3) group rather than to its axial CF(2) stretches. To our knowledge, this is the first report of SFG studies on semifluoroalkyl silane self-assembled films in the C-F stretching frequency region.     

The electronic structure and adsorption geometry of L-histidine on Cu(110)

The adsorption of L-histidine on clean and oxygen-covered Cu(110) surfaces has been studied by soft X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The valence band spectra, carbon, nitrogen and oxygen 1 s XPS and N K edge absorption spectra were measured for submonolayer, monolayer, and multilayer films. The spectra provide a detailed picture of the electronic structure and adsorption geometry at each coverage. In the monolayer, the histidine molecules are randomly oriented, in contrast to the submonolayer regime, where the molecules are coordinated to the copper surface with the imidazole functional group nearly parallel to, and strongly interacting with, the surface. The pi*/sigma* intensity ratio in NEXAFS spectra at the nitrogen edge varies strongly with angle, showing the imidazole ring is oriented. Adsorption models are proposed.     

胍基硅前驱体的合成及应用

以胍基取代的二甲基二氯硅烷与胺基锂反应合成了3种硅基化合物,使用核磁共振、高分辨质谱、元素分析对化合物结构进行了表征,通过热重分析(TGA)研究了化合物的热稳定性、挥发性、蒸汽压等性能。 3种化合物均具有良好的热稳定性及挥发性,无明显热分解过程,固体残留小于1%,接近纯挥发过程,最高蒸汽压在3600~5300 Pa,满足前驱体使用要求。 以二甲基-胍基-甲乙胺基-硅烷为前驱体,采用螺旋波等离子体气相沉积(HWPCVD)工艺制备了硅基薄膜,使用X射线光电子能谱(XPS)和扫描电子显微镜(SEM)分析了薄膜的化学组成和膜表面结构,XPS分析结果证实该薄膜为Si、N、C组成,实验结果表明,该类胍基硅化合物可作为硅基化学气相沉积(CVD)前驱体材料应用于集成电路制造。     

Preparation and Spectroscopic Characterization of Blue CoAl2O4 Coatings

Optically selective thin films of CoAl₂O₄ with a spinel structure were produced for an automotive lamps application by the sol-gel process using aluminum sec-butoxide, ethylacetoacetate chelating agent and cobalt nitrate hexahydrate. The use of two metal-oxide precursors is advantageous over the single bimetallic alkoxide precursor (aluminum cobalt isopropoxide), because it allows us to vary the Co/Al ratio in the precursor solution. We found that the Co/Al ratio should not exceed 0.3 if we are to achieve films with the characteristic blue colour at 700°C. The structural characteristics of the oxide powders were determined from infrared (IR) spectra and X-ray diffraction (XRD) analysis, while the optical properties of the films were investigated with UV-VIS spectroscopy.     

XPS study of the state of iridium, platinum, titanium and oxygen in thermally formed IrO2+TiO2+PtOX films

Electrodes of nominal composition Ir_0.3Ti_(0.7−x)Pt_xO₂ (x=0; 0.4 and 0.7) have been prepared by thermal decomposition of mixtures of the chloride precursors. H₂PtCl₆ was used as Pt-precursor. A systematic study of the chemical composition and oxidation states of the elements of these electrodes was performed by XPS. XPS analysis showed that the surface of the PtO_x-containing coatings are Pt enriched. Additionally, XPS revealed that the Ir signals are almost absent from the spectra of PtO_x-containing electrodes, while the Ti signal is completely absent. On the basis of the XPS results it is possible to propose a model of the surface structure of these electrodes: the grains, composed almost exclusively of Ir+Pt, are Pt enriched and distributed in a matrix, which although having Ti in its composition, besides Ir and Pt, is also Pt enriched. This finding corroborates the electrochemical behaviour of these electrodes, which is characteristic of polycrystalline Pt.     

Chemical characterisation of different separation media based on agarose by static time-of-flight secondary ion mass spectrometry

In this paper, the novel application of time-of-flight secondary ion mass spectrometry (TOF-SIMS) for qualitative and semi-quantitative investigation of the surface chemistry of separation media based on beaded agarose is reported. Five different media were studied: DEAE Sepharose Fast Flow, Q Sepharose Fast Flow, SP Sepharose Fast Flow, Phenyl Sepharose Fast Flow at ligand densities between 7 and 33% (w/w) and the base matrix Sepharose 6 Fast Flow. The obtained TOF-SIMS spectra reveal significant chemical information regarding the ligands (DEAE, Q, SP and Phenyl) which are covalently attached to the agarose-based matrix Sepharose 6 Fast Flow. For the anion-exchange media (DEAE and Q Sepharose Fast Flow), the positive TOF-SIMS spectra yielded several strong characteristic fragment peaks from the amine ligands. Structural information was obtained, e.g. from the peak at m/z 173.20, originating from the ion structure [(C2H5)2NCH2CH2NH(C2H5)2l+, which shows that the ligand in DEAE Sepharose Fast Flow is composed of both tertiary and quaternary amines. The positive spectrum of Phenyl Sepharose Fast Flow contained major fragments both from the base matrix and the ligand. The cation-exchanger (SP Sepharose Fast Flow) gave rise to a positive spectrum resembling that of the base matrix (Sepharose 6 Fast Flow) but with a different intensity pattern of the matrix fragments. In addition, peaks with low intensity at m/z 109.94, 125.94 and 139.95 corresponding to Na2SO2+, Na2SO3+ and Na2SO3CH2+, respectively, were observed. The positive TOF-SIMS spectrum of Sepharose 6 Fast Flow contains a large number of fragments in the mass range up to m/z 200 identified as CxHyOz and CxHy structures. The results clearly show that positive TOF-SIMS spectra of different media based on Sepharose 6 Fast Flow are strongly influenced by the ligand coupled to the matrix. The negative TOF-SIMS spectra contained several ligand-specific, characteristic peaks for the cation-exchanger, having sulphonate as the ion-exchange group. Negative fragments such as S-, SO-, SO2-, SO3-, C2H3SO3-, C3H5SO3- and OC3H5SO3- were observed. Phenyl Sepharose Fast Flow, which has an uncharged group (Phenyl) coupled to the agarose matrix yielded one ligand-related peak corresponding to the C6H5O- fragment. DEAE and Q ligands could only be identified by the appearance of the fragments CN- and CNO- in the negative spectrum. However, a strong peak corresponding to the counter ion (Cl-) was observed. TOF-SIMS analysis can also be used for the investigation of residues from the coupling procedure that bonds the ligands to the matrix. One example is the observation of bromine peaks in the negative spectrum of Q Sepharose Fast Flow. Furthermore, it has also been shown that different ligand concentrations of Phenyl Sepharose Fast Flow can easily be detected by TOF-SIMS analysis. Information regarding the difference between the ligand density on the surface of the beads and in the bulk can also be obtained. However, spectra registered on the outermost surface and on the pore surface (crushed beads) of DEAE Sepharose Fast Flow clearly show that the agarose and the DEAE groups are homogeneously distributed in the beads.     

Dual parallel electrospray ionization and atmospheric pressure chemical ionization mass spectrometry (MS), MS/MS and MS/MS/MS for the analysis of triacylglycerols and triacylglycerol oxidation products

Two mass spectrometers, in parallel, were employed simultaneously for analysis of triacylglycerols in canola oil, for analysis of triolein oxidation products, and for analysis of triacylglycerol positional isomers separated using reversed-phase high-performance liquid chromatography. A triple quadrupole mass spectrometer was interfaced via an atmospheric pressure chemical ionization (APCI) interface to two reversed-phase liquid chromatographic columns in series. An ion trap mass spectrometer was coupled to the same two columns using an electrospray ionization (ESI) interface, with ammonium formate added as electrolyte. Electrospray ionization mass spectrometry (ESI-MS) under these conditions produced abundant ammonium adduct ions from triacylglycerols, which were then fragmented to produce MS/MS spectra and then fragmented further to produce MS/MS/MS spectra. ESI-MS/MS of the ammoniated adduct ions gave product ion mass spectra which were similar to mass spectra obtained by APCI-MS. ESI-MS/MS produced diacylglycerol fragment ions, and additional fragmentation (MS/MS/MS) produced [RCO](+) (acylium) ions, [RCOO+58](+) ions, and other related ions which allowed assignment of individual acyl chain identities. APCI-MS of triacylglycerol oxidation products produced spectra like those reported previously using APCI-MS. APCI-MS/MS produced ions related to individual fatty acid chains. ESI-MS of triacylglycerol oxidation products produced abundant ammonium adduct ions, even for those molecules which previously produced little or no intact molecular ions under APCI-MS conditions. Fragmentation (MS/MS) of the [M+NH(4)](+) ions produced results similar to those obtained by APCI-MS. Further fragmentation (MS/MS/MS) of the diacylglycerol fragments of oxidation products provided information on the oxidized individual fatty acyl chains. ESI-MS and APCI-MS were found to be complementary techniques, which together contributed to a better understanding of the identities of the products formed by oxidation of triacylglycerols.     

DC-plasma polymerization of pyrrole

DC-plasma-polymerized pyrrole (PP-Py) films deposited on metals were extensively characterized by Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), Reflection-Absorption IR Spectroscopy (RAIR), X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM), Glow Discharge Optical Spectroscopy (GDOS), electrical conductivity (ASTM Franklin test), and contact angle measurements. TOF-SIMS and RAIR showed no spectroscopic evidence of the presence of the pyrrole ring structure in any of the plasmadeposited films. The major parameter that affected their composition was found to be the pressure. Films deposited at low pressure were less hydrogenated than those polymerized at high pressure or in remote plasma conditions. Although all deposits oxidized slowly in air, their surface energy remained low over an extended period of time. The electrical conductivity of the PP-Py films was in the range of 10⁻³–10⁻⁴ S/cm, i.e., higher than that of amorphous carbon films.     

The Surface Modification of Pure Cellulose Paper Induced by Low-Pressure Nitrogen Plasma Treatment

We have used Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) in combination with X-ray photoelectron spectroscopy (XPS) to study chemical changes taking place at the surface of pure cellulose paper samples treated in N₂ plasma for periods of time up to 60 seconds. High resolution TOF-SIMS spectra permit the detection of various functionalities containing nitrogen, even following very brief (2s) plasma exposure. Correlations between chemistry and surface properties, such as water wettability, are presented and discussed.