Behnam Moeini, Tahereh G. Avval, Neal Gallagher, M. Linford
This Insight Note follows two previous Insight Notes on X‐ray photoelectron spectroscopy (XPS) image analysis that dealt with the importance of analyzing the raw data and the use of summary statistics. As a next step in the exploratory data analysis (EDA) of XPS images, we now show principal component analysis (PCA) of an XPS image. PCA is appropriate when the spectra in a data set are correlated to some degree and the noise in the spectra is unimportant. In these cases, PCA can significantly reduce the dimensionality and complexity of data sets. Preprocessing is an important part of many PCAs. Its usefulness is illustrated with a small, mock data set, where the potential pitfalls of not preprocessing are shown. PCAs of XPS image data that were not preprocessed and preprocessed by mean centering are illustrated. Scree plots, which are used to determine the number of abstract factors (principal components, PCs) that describe a data set, are shown. The spectra in our XPS image are quite noisy, which is consistent with the moderate, but still significant, amount of variance that is captured by the first two PCs in our PCA. With both preprocessing methods, the loadings on PC1 and PC2 are remarkably smooth. The loadings on the next six PCs also appear to contain some chemical information. Scores images generated using both no preprocessing and preprocessing by mean centering reveal many of the same general features in the data set that were found in our two previous Insight Notes.
{"title":"Surface analysis insight note. Principal component analysis (PCA) of an X‐ray photoelectron spectroscopy image. The importance of preprocessing","authors":"Behnam Moeini, Tahereh G. Avval, Neal Gallagher, M. Linford","doi":"10.1002/sia.7252","DOIUrl":"https://doi.org/10.1002/sia.7252","url":null,"abstract":"This Insight Note follows two previous Insight Notes on X‐ray photoelectron spectroscopy (XPS) image analysis that dealt with the importance of analyzing the raw data and the use of summary statistics. As a next step in the exploratory data analysis (EDA) of XPS images, we now show principal component analysis (PCA) of an XPS image. PCA is appropriate when the spectra in a data set are correlated to some degree and the noise in the spectra is unimportant. In these cases, PCA can significantly reduce the dimensionality and complexity of data sets. Preprocessing is an important part of many PCAs. Its usefulness is illustrated with a small, mock data set, where the potential pitfalls of not preprocessing are shown. PCAs of XPS image data that were not preprocessed and preprocessed by mean centering are illustrated. Scree plots, which are used to determine the number of abstract factors (principal components, PCs) that describe a data set, are shown. The spectra in our XPS image are quite noisy, which is consistent with the moderate, but still significant, amount of variance that is captured by the first two PCs in our PCA. With both preprocessing methods, the loadings on PC1 and PC2 are remarkably smooth. The loadings on the next six PCs also appear to contain some chemical information. Scores images generated using both no preprocessing and preprocessing by mean centering reveal many of the same general features in the data set that were found in our two previous Insight Notes.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41967259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tian-qiu Hong, Lin Wei, Ziyue Li, Yuanhui Wang, Qiang Zhang, Lei Luo, Tingting Zhang, Ruolan Li, Yiming Tang
The acid–base surface properties of vivianite crystals highly affect the adsorption capacity of vivianite for heavy metals and organic matters in aqueous solution. Therefore, the aim of the study was to innovatively explore and quantify the acid–base surface characterization of vivianite crystals in aqueous solution. It was found that the two surface active adsorption sites (≡POH and ≡FeOH) and five surface species thereof (i.e., ≡PO, ≡POH, ≡FeOH, ≡FeO−, and ≡FeOH2+) underwent surface reaction on vivianite crystals. Moreover, the active surface site and point of zero charge of vivianite crystals were 18 sites/nm2 and pH 5.9. Importantly, constant capacitance model was successfully employed to model the titration data, from which the distribution of surface species as function of pH and surface reaction constants were also accurately derived. The finding herein can be applied for plausible modeling molecular‐scale adsorption of the impurities on vivianite surface.
{"title":"Exploring the acid‐base surface properties of vivianite crystals in aqueous solution","authors":"Tian-qiu Hong, Lin Wei, Ziyue Li, Yuanhui Wang, Qiang Zhang, Lei Luo, Tingting Zhang, Ruolan Li, Yiming Tang","doi":"10.1002/sia.7253","DOIUrl":"https://doi.org/10.1002/sia.7253","url":null,"abstract":"The acid–base surface properties of vivianite crystals highly affect the adsorption capacity of vivianite for heavy metals and organic matters in aqueous solution. Therefore, the aim of the study was to innovatively explore and quantify the acid–base surface characterization of vivianite crystals in aqueous solution. It was found that the two surface active adsorption sites (≡POH and ≡FeOH) and five surface species thereof (i.e., ≡PO, ≡POH, ≡FeOH, ≡FeO−, and ≡FeOH2+) underwent surface reaction on vivianite crystals. Moreover, the active surface site and point of zero charge of vivianite crystals were 18 sites/nm2 and pH 5.9. Importantly, constant capacitance model was successfully employed to model the titration data, from which the distribution of surface species as function of pH and surface reaction constants were also accurately derived. The finding herein can be applied for plausible modeling molecular‐scale adsorption of the impurities on vivianite surface.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45046616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Zulaehah, E. Saputra, R. Jonuarti, W. T. Cahyanto
{"title":"A first principles study on the catalytic performance of methylcyclohexane dehydrogenation on a monoatomic catalyst","authors":"S. Zulaehah, E. Saputra, R. Jonuarti, W. T. Cahyanto","doi":"10.1002/sia.7251","DOIUrl":"https://doi.org/10.1002/sia.7251","url":null,"abstract":"","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45471705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
TiSiCN composite coatings with different C contents were prepared on Cr buffer layer by plasma‐enhanced magnetron sputtering. The structure, composition, surface, and cross‐sectional morphology of the coatings were characterized by X‐ray photoelectron spectroscopy, X‐ray diffraction, Raman spectroscopy, scanning electron microscope, and atomic force microscope. The hardness, elastic modulus, and tribological performance of the coatings were evaluated by nanoindentation and reciprocating friction tests. The results showed that the TiSiCN composite coatings are amorphous structure composed of TiCN compound and microcrystalline graphite, and amorphous phases. The increase of C content changed the content and distribution of TiCN ceramics nanocrystal, amorphous Si3N4 and amorphous carbon (sp3‐ and sp2‐hybridized C), thus affecting the hardness and friction behavior of the coatings. The hardness of the composite coatings was related to the content of TiCN phase and sp3‐C in the coatings. The TiSiCN composite coating with C content of 68.2% had lower coefficient of friction and the lowest wear rate.
{"title":"Microstructure and tribological properties of TiSiCN composite coatings with different carbon contents deposited by plasma‐enhanced magnetron sputtering","authors":"Zhubo Liu, Wantao Jin, B. Zhou, Linan Ma, Xiaoguang Ma, Jing-Wei Zhao","doi":"10.1002/sia.7250","DOIUrl":"https://doi.org/10.1002/sia.7250","url":null,"abstract":"TiSiCN composite coatings with different C contents were prepared on Cr buffer layer by plasma‐enhanced magnetron sputtering. The structure, composition, surface, and cross‐sectional morphology of the coatings were characterized by X‐ray photoelectron spectroscopy, X‐ray diffraction, Raman spectroscopy, scanning electron microscope, and atomic force microscope. The hardness, elastic modulus, and tribological performance of the coatings were evaluated by nanoindentation and reciprocating friction tests. The results showed that the TiSiCN composite coatings are amorphous structure composed of TiCN compound and microcrystalline graphite, and amorphous phases. The increase of C content changed the content and distribution of TiCN ceramics nanocrystal, amorphous Si3N4 and amorphous carbon (sp3‐ and sp2‐hybridized C), thus affecting the hardness and friction behavior of the coatings. The hardness of the composite coatings was related to the content of TiCN phase and sp3‐C in the coatings. The TiSiCN composite coating with C content of 68.2% had lower coefficient of friction and the lowest wear rate.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44554797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nur Afieqah Md. Ghazazi, S. Liza, J. Ishimatsu, N. A. Mat Tahir, Nur Aszreen Zulkifli, Y. Yaakob
Anodizing is widely used as a surface treatment for aluminum alloy to improve its surface properties by increasing the thickness of the oxide layer. Generally, conventional anodizing by direct current (DC) produced high porosity and micro‐cracks. Utilizing pulse current (PC) as a power source and graphite particles as reinforcement for the oxide layer may solve these problems. Therefore, the present work aims to study the effect of the combination approaches on coating growth and the surface characteristics of the oxide coating. The graphite‐incorporated composite oxide coating on the AA2017‐T4 Al alloy was developed by DC and PC hard anodizing process. The surface morphology, topography, chemical composition, and surface hardness were evaluated. In PC anodizing, the growth rate of oxide layer was slower (0.59 μm/min) than DC anodizing (1.08 μm/min). The surface pores start to develop at the 30th minute compared to DC, which is the 20th minute. At 60 min, the formation of porous composite oxide coating is complete with pore dimension (width: 46.74 ± 19.96 μm and depth: 7.11 ± 2.57 μm) and thickness of 35.20 ± 8.90 μm for PC, whereas for DC pore dimension (width: 81.03 ± 21.60 μm and depth: 17.16 ± 4.31 μm) and thickness of 64.80 ± 23.69 μm. Surface roughness and hardness of composite oxide coating by PC were measured at about 1.90 ± 0.04 μm and 379.10 ± 4.37 HV, respectively. Meanwhile, the DC reveals a significant increase in roughness (4.28 ± 0.25 μm) and a decrease in hardness (302.75 ± 1.09 HV). The introduction of graphite particles with PC anodizing reduces the surface porosity, microcracks and enhances the surface hardness of oxide coating.
{"title":"Effect of pulse current on surface properties of aluminum oxide coating containing graphite","authors":"Nur Afieqah Md. Ghazazi, S. Liza, J. Ishimatsu, N. A. Mat Tahir, Nur Aszreen Zulkifli, Y. Yaakob","doi":"10.1002/sia.7249","DOIUrl":"https://doi.org/10.1002/sia.7249","url":null,"abstract":"Anodizing is widely used as a surface treatment for aluminum alloy to improve its surface properties by increasing the thickness of the oxide layer. Generally, conventional anodizing by direct current (DC) produced high porosity and micro‐cracks. Utilizing pulse current (PC) as a power source and graphite particles as reinforcement for the oxide layer may solve these problems. Therefore, the present work aims to study the effect of the combination approaches on coating growth and the surface characteristics of the oxide coating. The graphite‐incorporated composite oxide coating on the AA2017‐T4 Al alloy was developed by DC and PC hard anodizing process. The surface morphology, topography, chemical composition, and surface hardness were evaluated. In PC anodizing, the growth rate of oxide layer was slower (0.59 μm/min) than DC anodizing (1.08 μm/min). The surface pores start to develop at the 30th minute compared to DC, which is the 20th minute. At 60 min, the formation of porous composite oxide coating is complete with pore dimension (width: 46.74 ± 19.96 μm and depth: 7.11 ± 2.57 μm) and thickness of 35.20 ± 8.90 μm for PC, whereas for DC pore dimension (width: 81.03 ± 21.60 μm and depth: 17.16 ± 4.31 μm) and thickness of 64.80 ± 23.69 μm. Surface roughness and hardness of composite oxide coating by PC were measured at about 1.90 ± 0.04 μm and 379.10 ± 4.37 HV, respectively. Meanwhile, the DC reveals a significant increase in roughness (4.28 ± 0.25 μm) and a decrease in hardness (302.75 ± 1.09 HV). The introduction of graphite particles with PC anodizing reduces the surface porosity, microcracks and enhances the surface hardness of oxide coating.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44313275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developments in X‐ray photoelectron spectroscopy (XPS) instrumentation and the need for spatial information in surface characterization have led to advances in XPS imaging and related image processing techniques. In this Insight Note, we demonstrate the use of summary statistics as simple, but effective, tools for understanding XPS hyperspectral images (data cubes) prior to more advanced image processing. An XPS image obtained from a silicon surface patterned with different thicknesses of oxide was analyzed with three summary statistics: a tool in the MATLAB programming environment, the mean, and pattern recognition entropy (PRE). The MATLAB tool largely separates the spectra into two groups. The mean does a somewhat better job differentiating between the spectra, and PRE is even more effective. The results of the MATLAB summary statistic are confirmed by plotting the average and standard deviation spectra of different regions of the image it produces. The results of the mean and PRE summary statistics are confirmed by evenly segmenting the results and examining the average and standard deviation spectra of these segments. Fitting these average spectra demonstrates the greater effectiveness of the PRE summary statistic in segmenting the spectra into chemically distinct groups.
{"title":"Surface analysis insight note: Analysis of X‐ray photoelectron spectroscopy images with summary statistics","authors":"Behnam Moeini, M. Linford","doi":"10.1002/sia.7248","DOIUrl":"https://doi.org/10.1002/sia.7248","url":null,"abstract":"Developments in X‐ray photoelectron spectroscopy (XPS) instrumentation and the need for spatial information in surface characterization have led to advances in XPS imaging and related image processing techniques. In this Insight Note, we demonstrate the use of summary statistics as simple, but effective, tools for understanding XPS hyperspectral images (data cubes) prior to more advanced image processing. An XPS image obtained from a silicon surface patterned with different thicknesses of oxide was analyzed with three summary statistics: a tool in the MATLAB programming environment, the mean, and pattern recognition entropy (PRE). The MATLAB tool largely separates the spectra into two groups. The mean does a somewhat better job differentiating between the spectra, and PRE is even more effective. The results of the MATLAB summary statistic are confirmed by plotting the average and standard deviation spectra of different regions of the image it produces. The results of the mean and PRE summary statistics are confirmed by evenly segmenting the results and examining the average and standard deviation spectra of these segments. Fitting these average spectra demonstrates the greater effectiveness of the PRE summary statistic in segmenting the spectra into chemically distinct groups.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48893471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. B. Tripathy, H. Rath, N. C. Mishra, Jayashree Das, D. Mishra
The effect of swift heavy ion irradiation on structural, optical, and microstructural properties of TiO2 has been studied. Pellets prepared from TiO2 nanoparticles have been irradiated by 120 MeV Ag ions at different fluences ranging from 5 × 1011 to 1 × 1013 ions cm−2. X‐ray diffraction (XRD), Raman, UV–visible, and photoluminescence (PL) studies indicated anatase phase both in as‐prepared and irradiated pellets. XRD study revealed the crystallite size of the particles as ~16 nm, which is close to the upper limit of the particle size where anatase phase is most stable. Our study thus established the importance of the initial microstructure on the irradiation response of the nanoparticles. Though irradiation did not affect the crystal structure and the polycrystalline nature of the anatase TiO2, it suppressed the crystalline volume fraction. Poisson fitting of the suppression of XRD peak area with irradiation fluence revealed radius of the track of each 120 MeV Ag ion in TiO2 nanoparticles as ~2.1 nm. Irradiation, in addition to creating disorder, darkened the surface of the pellets because of the creation of oxygen vacancies in the TiO6 octahedra. Reorganization of these defects led to suppression of the band gap of TiO2 nanoparticles from 3.19 eV of the pristine sample to 3 eV for samples irradiated beyond a critical fluences 3 × 1012 ions cm−2. The size of the nanoparticles and their agglomeration remained unaffected by irradiation as indicated by field emission scanning electron micrographs.
{"title":"Surface modifications of TiO2 nanostructured materials induced by 120 MeV Ag ions","authors":"B. B. Tripathy, H. Rath, N. C. Mishra, Jayashree Das, D. Mishra","doi":"10.1002/sia.7247","DOIUrl":"https://doi.org/10.1002/sia.7247","url":null,"abstract":"The effect of swift heavy ion irradiation on structural, optical, and microstructural properties of TiO2 has been studied. Pellets prepared from TiO2 nanoparticles have been irradiated by 120 MeV Ag ions at different fluences ranging from 5 × 1011 to 1 × 1013 ions cm−2. X‐ray diffraction (XRD), Raman, UV–visible, and photoluminescence (PL) studies indicated anatase phase both in as‐prepared and irradiated pellets. XRD study revealed the crystallite size of the particles as ~16 nm, which is close to the upper limit of the particle size where anatase phase is most stable. Our study thus established the importance of the initial microstructure on the irradiation response of the nanoparticles. Though irradiation did not affect the crystal structure and the polycrystalline nature of the anatase TiO2, it suppressed the crystalline volume fraction. Poisson fitting of the suppression of XRD peak area with irradiation fluence revealed radius of the track of each 120 MeV Ag ion in TiO2 nanoparticles as ~2.1 nm. Irradiation, in addition to creating disorder, darkened the surface of the pellets because of the creation of oxygen vacancies in the TiO6 octahedra. Reorganization of these defects led to suppression of the band gap of TiO2 nanoparticles from 3.19 eV of the pristine sample to 3 eV for samples irradiated beyond a critical fluences 3 × 1012 ions cm−2. The size of the nanoparticles and their agglomeration remained unaffected by irradiation as indicated by field emission scanning electron micrographs.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42169081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Adam M. Morgan, J. D. Henderson, B. Kobe, M. Biesinger, J. Noël
X‐ray photoelectron spectroscopy (XPS) is a technique that is widely used to study thin oxide films because of its extremely high surface sensitivity. Utilizing the QUASES (Quantitative Analysis of Surfaces by Electron Spectroscopy) software package developed by Sven Tougaard (University of Southern Denmark), a user can obtain additional information that is not extracted in conventional XPS analysis, specifically the composition as a function of depth. Presented here is the QUASES analysis of four Ni‐Cr‐Mo alloys performed while testing various inelastic mean free path (IMFP) determination methods in the context of providing a framework for the analysis of complex oxides in QUASES. Ni‐Cr‐Mo alloys are often used to replace conventional materials under aggressive conditions, because of their exceptional corrosion resistance. Their corrosion resistance is conferred by the formation of an inert surface oxide film that protects the underlying metal. Using the QUASES software, the thickness of the air‐formed oxide on four Ni‐Cr‐Mo alloys was found to lie within the range of 2.5–3.6 nm. They were found to be composed of an inner Cr2O3 layer and an outer Cr (OH)3 layer, with a transition zone where the two coexisted. Oxidized Mo species, MoO2 and MoO3, were found in trace amounts at the boundary between the Cr2O3‐only and mixed Cr2O3/Cr (OH)3 regions of the oxide. We also determined that using 20% reduced IMFP values gave results similar to those obtained using electron effective attenuation length (EAL) values. Auger depth profiles showed comparable trends to the QUASES models.
{"title":"Investigating the structure of the oxide on Ni‐Cr‐Mo alloys while presenting a method for analysis of complex oxides using QUASES","authors":"Adam M. Morgan, J. D. Henderson, B. Kobe, M. Biesinger, J. Noël","doi":"10.1002/sia.7243","DOIUrl":"https://doi.org/10.1002/sia.7243","url":null,"abstract":"X‐ray photoelectron spectroscopy (XPS) is a technique that is widely used to study thin oxide films because of its extremely high surface sensitivity. Utilizing the QUASES (Quantitative Analysis of Surfaces by Electron Spectroscopy) software package developed by Sven Tougaard (University of Southern Denmark), a user can obtain additional information that is not extracted in conventional XPS analysis, specifically the composition as a function of depth. Presented here is the QUASES analysis of four Ni‐Cr‐Mo alloys performed while testing various inelastic mean free path (IMFP) determination methods in the context of providing a framework for the analysis of complex oxides in QUASES. Ni‐Cr‐Mo alloys are often used to replace conventional materials under aggressive conditions, because of their exceptional corrosion resistance. Their corrosion resistance is conferred by the formation of an inert surface oxide film that protects the underlying metal. Using the QUASES software, the thickness of the air‐formed oxide on four Ni‐Cr‐Mo alloys was found to lie within the range of 2.5–3.6 nm. They were found to be composed of an inner Cr2O3 layer and an outer Cr (OH)3 layer, with a transition zone where the two coexisted. Oxidized Mo species, MoO2 and MoO3, were found in trace amounts at the boundary between the Cr2O3‐only and mixed Cr2O3/Cr (OH)3 regions of the oxide. We also determined that using 20% reduced IMFP values gave results similar to those obtained using electron effective attenuation length (EAL) values. Auger depth profiles showed comparable trends to the QUASES models.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42621879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michelle D. Sullivan, W. Pinson, Troy Eberhardt, Jonathan J Ross, Tyler W. Wood
The physicochemical events at ink intersections are largely understudied. Chemical imaging techniques and multivariate analyses applied to this problem thus far lack the performance characteristics to make confident conclusions about these processes. This deficiency leads to subjective and controversial deposition order determinations in forensic investigations. In this comprehensive report, 44 unique crossings involving laser toners and stamps, as well as felt‐tip, rollerball, gel, and ballpoint pen inks, were imaged with X‐ray photoelectron spectroscopy (XPS), using a 50‐μm X‐ray spot size and 100‐μm steps. The specificity and surface sensitivity of XPS enabled the objective visualization of the inks' chemistry upon deposition via spatial elemental distribution in‐situ. Signal intensity and atomic concentration were mapped for each element detected. Discrimination was possible in 100% of written and printed inks analyzed, and the relationship between the elemental concentration profile in each intersection was compared with the known sequence. Formation of ink layers, mixing, and separation of ink components by way of electrostatic forces were observed. Insights into the known complexity of ink intersection processes were revealed and highlight the need for understanding the chosen analytical technique's information depth and for complementary analyses to increase sequencing confidence. We also provide evidence that these processes invalidate the utility of principal component analysis for analyzing ink intersections. However, sequencing accuracy was 84% for all samples analyzed, and its success was highly dependent on the presence of physical features (i.e., thick coatings and embossed regions). In some intersection types, especially toners, the features exposed with XPS imaging enabled a sequencing accuracy of 100%.
{"title":"Deposition order and physicochemical process visualization of ink intersections using X‐ray photoelectron spectroscopy imaging for forensic analysis","authors":"Michelle D. Sullivan, W. Pinson, Troy Eberhardt, Jonathan J Ross, Tyler W. Wood","doi":"10.1002/sia.7246","DOIUrl":"https://doi.org/10.1002/sia.7246","url":null,"abstract":"The physicochemical events at ink intersections are largely understudied. Chemical imaging techniques and multivariate analyses applied to this problem thus far lack the performance characteristics to make confident conclusions about these processes. This deficiency leads to subjective and controversial deposition order determinations in forensic investigations. In this comprehensive report, 44 unique crossings involving laser toners and stamps, as well as felt‐tip, rollerball, gel, and ballpoint pen inks, were imaged with X‐ray photoelectron spectroscopy (XPS), using a 50‐μm X‐ray spot size and 100‐μm steps. The specificity and surface sensitivity of XPS enabled the objective visualization of the inks' chemistry upon deposition via spatial elemental distribution in‐situ. Signal intensity and atomic concentration were mapped for each element detected. Discrimination was possible in 100% of written and printed inks analyzed, and the relationship between the elemental concentration profile in each intersection was compared with the known sequence. Formation of ink layers, mixing, and separation of ink components by way of electrostatic forces were observed. Insights into the known complexity of ink intersection processes were revealed and highlight the need for understanding the chosen analytical technique's information depth and for complementary analyses to increase sequencing confidence. We also provide evidence that these processes invalidate the utility of principal component analysis for analyzing ink intersections. However, sequencing accuracy was 84% for all samples analyzed, and its success was highly dependent on the presence of physical features (i.e., thick coatings and embossed regions). In some intersection types, especially toners, the features exposed with XPS imaging enabled a sequencing accuracy of 100%.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47579760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information","authors":"","doi":"10.1002/sia.7118","DOIUrl":"https://doi.org/10.1002/sia.7118","url":null,"abstract":"No abstract is available for this article.","PeriodicalId":22062,"journal":{"name":"Surface and Interface Analysis","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42470710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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