Tim May
University of Saskatchewan, Canadian Light Source, Faculty Member
- Senior scientist at CLS synchrotron light source interested in infrared spectroscopy and instrumentation.edit
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The application of a micro-Fourier transform infrared, (μ-FTIR), spectroscopic system, using synchrotron radiation as a light source, for photoresist chemical analysis has been investigated. The better signal to noise due to the high... more
The application of a micro-Fourier transform infrared, (μ-FTIR), spectroscopic system, using synchrotron radiation as a light source, for photoresist chemical analysis has been investigated. The better signal to noise due to the high brightness of the infrared radiation from the synchrotron ...
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The demand of smaller device dimensions drives the need to improve the lithographic and the metrology tools to produce them. Characterization of the image formation during the lithography process is key to any process control effort.... more
The demand of smaller device dimensions drives the need to improve the lithographic and the metrology tools to produce them. Characterization of the image formation during the lithography process is key to any process control effort. Scanning probe microscopy (SPM) on ...
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Synchrotron radiation from the new Canadian Light Source facility has been used to obtain a high resolution (0.0012 cm$^{-1})$ absorption spectrum of acrolein vapor in the 550-660 cm$^{-1}$ region. Almost 2000 transitions have been... more
Synchrotron radiation from the new Canadian Light Source facility has been used to obtain a high resolution (0.0012 cm$^{-1})$ absorption spectrum of acrolein vapor in the 550-660 cm$^{-1}$ region. Almost 2000 transitions have been included in a detailed analysis of ...
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Solvent properties play a central role in mediating the aggregation and self-assembly of molecular gelators and their growth into fibers. Numerous attempts have been made to correlate solubility parameters of solvents and gelation... more
Solvent properties play a central role in mediating the aggregation and self-assembly of molecular gelators and their growth into fibers. Numerous attempts have been made to correlate solubility parameters of solvents and gelation abilities of molecular gelators, but a comprehensive comparison of the most important parameters has yet to appear. Here, the degree to which partition coefficients (logP), Henry's law constants (HLC), dipole moments, static relative permittivities (εr), solvatochromic ET(30) parameters, Kamlet-Taft parameters (β, α and π), Catalan's solvatochromic parameters (SPP, SB and SA), Hildebrand solubility parameters (δi), and Hansen solubility parameters (δp, δd, δh) and the associated Hansen distance ( Rij) of 62 solvents (covering a wide range of properties) can be correlated with the self-assembly and gelation of 1,3:2,4-dibenzylidene sorbitol (DBS) gelation, a classic molecular gelator, is assessed systematically. The approach presented describes the ...
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Knowledge Bank. Search Knowledge Bank. Advanced Search. Home. About the Knowledge Bank FAQs Policies Video Procedures Community Setup Form Describing Your Resources Knowledge Bank License Agreement Go. Browse. Communities &... more
Knowledge Bank. Search Knowledge Bank. Advanced Search. Home. About the Knowledge Bank FAQs Policies Video Procedures Community Setup Form Describing Your Resources Knowledge Bank License Agreement Go. Browse. Communities & Collections. Issue Date. ...
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Limitations of conventional light microscopy in pathological diagnosis of brain tumors include subjective bias in interpretation and discordance of nomenclature. A study using mid-infrared (IR) spectromicroscopy was undertaken to... more
Limitations of conventional light microscopy in pathological diagnosis of brain tumors include subjective bias in interpretation and discordance of nomenclature. A study using mid-infrared (IR) spectromicroscopy was undertaken to determine whether meningiomas, a group of brain tumors prone to recurrence, could be identified by the unique spectral 'fingerprints' of their chemical composition. Paired, thin (5-microm) cryosections of snap-frozen human meningioma tumor samples removed at elective surgery were mounted on glass (hematoxylin and eosin-stained tissue section) and infrared (unstained tissue section) reflectance slides, respectively. Concordance of the tumor-bearing areas identified in the stained section by a pathologist with the unstained IR tissue section was ensured using a novel digital grid and tumor-mapping system developed in our laboratory. Compared with the normal control, tumor samples from four meningioma patients revealed a marked decrease in bands associ...
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Knowledge Bank. Search Knowledge Bank. Advanced Search. Home. About the Knowledge Bank FAQs Policies Video Procedures Community Setup Form Describing Your Resources Knowledge Bank License Agreement Go. Browse. Communities &... more
Knowledge Bank. Search Knowledge Bank. Advanced Search. Home. About the Knowledge Bank FAQs Policies Video Procedures Community Setup Form Describing Your Resources Knowledge Bank License Agreement Go. Browse. Communities & Collections. Issue Date. ...
ABSTRACT Multi-beam wide-field imaging using synchrotron mid-infrared light sources coupled with focal plane array detectors has provided a major breakthrough to the field of bio-spectroscopic imaging. The ability to collect sub-cellular... more
ABSTRACT Multi-beam wide-field imaging using synchrotron mid-infrared light sources coupled with focal plane array detectors has provided a major breakthrough to the field of bio-spectroscopic imaging. The ability to collect sub-cellular molecular images in minutes has opened the door to a new era of biochemical studies. Although a multi-beam approach is the superior method to this form of imaging, it requires a specialised set of beamline optics, which may not be compatible with existing mid-infrared microscopy beamlines, or research programs/applications currently in place (some of which do not require an imaging component). In this investigation we demonstrate that a single-beam approach can be utilised in a similar manner to multi-beam imaging, to collect sub-cellular biochemical images of brain neurons in a rapid time frame, without extensive modification of an existing beamline configuration. This study uses an applied example, imaging the same neuron in situ within a brain tissue section, with both synchrotron and thermal sources. The results highlight the advantage of improved spatial resolution/image quality and spectral quality (signal to noise ratio) that is obtained when a high magnification and high numerical aperture objective (52x, 0.65) is coupled to a synchrotron mid-infrared lightsource with a focal plane array detector. The approach we report may prove to be particularly appealing to numerous existing mid-infrared beamlines, allowing straightforward integration of sub-cellular biochemical imaging with existing non-imaging research applications.
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Infrared Beamlines at the Canadian Light Source. [AIP Conference Proceedings 879, 579 (2007)]. Tim May, Dominique Appadoo, Thomas Ellis, Ruben Reininger. Abstract. The Canadian Light Source (CLS) is commissioning two infrared beamlines. ...
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ABSTRACT The observation of Multi-bunch interference with coherent synchrotron radiation at the Canadian Light Source is discussed along with the possibility that some of the spectral features are driven by the radiation impedance of the... more
ABSTRACT The observation of Multi-bunch interference with coherent synchrotron radiation at the Canadian Light Source is discussed along with the possibility that some of the spectral features are driven by the radiation impedance of the vacuum chamber.
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Solvent properties play a central role in mediating the aggregation and self-assembly of molecular gelators and their growth into fibers. Numerous attempts have been made to correlate the solubility parameters of solvents and gelation... more
Solvent properties play a central role in mediating the aggregation and self-assembly of molecular gelators and their growth into fibers. Numerous attempts have been made to correlate the solubility parameters of solvents and gelation abilities of molecular gelators, but a comprehensive comparison of the most important parameters has yet to appear. Here, the degree to which partition coefficients (log P), Henry's law constants (HLC), dipole moments, static relative permittivities (ε(r)), solvatochromic E(T)(30) parameters, Kamlet-Taft parameters (β, α, and π), Catalan's solvatochromic parameters (SPP, SB, and SA), Hildebrand solubility parameters (δ(i)), and Hansen solubility parameters (δ(p), δ(d), δ(h)) and the associated Hansen distance (R(ij)) of 62 solvents (covering a wide range of properties) can be correlated with the self-assembly and gelation of 1,3:2,4-dibenzylidene sorbitol (DBS) gelation, a classic molecular gelator, is assessed systematically. The approach pres...
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Glioblastoma multiforme (GBM) is one of the most malignant human tumors, with a uniformly poor outcome. One obstacle in curing malignant brain tumors is the limitation of conventional light microscopy in detecting microscopic residual... more
Glioblastoma multiforme (GBM) is one of the most malignant human tumors, with a uniformly poor outcome. One obstacle in curing malignant brain tumors is the limitation of conventional light microscopy in detecting microscopic residual tumor in biopsy samples from the perimeter of the surgically resected tumor. We further refined the identification of GBM tumor tissue at the sub-cellular level, utilising the technique of Synchrotron, sourced mid-infrared (mid-IR) spectromicroscopy. Paired, thin (5 microm) cryosections of snap-frozen human GBM tumor samples removed at elective surgery were mounted on glass slides (hematoxylin and eosin-stained tissue section) and calcium fluoride (CaF2) windows (unstained tissue section for transmission spectromicroscopy), respectively. Concordance of tumor bearing areas identified in the stained section with the unstained IR tissue section was confirmed by the pathologist of the study. Compared with molecular signatures obtained from normal control b...
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The formation kinetics of self-assembling tubules composed of phytosterol:gamma-oryzanol mixtures were investigated at the Canadian Light Source on the mid-IR beamline using synchrotron radiation and Fourier transform infrared... more
The formation kinetics of self-assembling tubules composed of phytosterol:gamma-oryzanol mixtures were investigated at the Canadian Light Source on the mid-IR beamline using synchrotron radiation and Fourier transform infrared spectroscopy (FT-IR). The Avrami model was fitted to the changing hydrogen bonding density occurring at 3450 cm(-1). The nucleation process was found to be highly dependent on the molecular structure of the phytosterol. The nucleation event for cholesterol:gamma-oryzanol was determined to be sporadic whereas 5alpha-cholestan-3beta-ol:gamma-oryzanol and beta-sitosterol:gamma-oryzanol underwent instantaneous nucleation. One-dimensional growth occurred for each phytosterol:gamma-oryzanol mixture and involved the evolution of highly specific intermolecular hydrogen bonds. More detailed studies on the cholesterol:gamma-oryzanol system indicated that the nucleation activation energy, determined from multiple rate constants, obtained using the Avrami model, was at a minimum when the two compounds were at a 1:1 weight ratio. This resulted in drastic differences to the microscopic structures and affected the macroscopic properties such as turbidity. The formation of the phytosterol:gamma-oryzanol complex was due to intermolecular hydrogen bonding, which was in agreement with the infrared spectroscopic evidence.
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The commissioning of synchrotron radiation (SR) photoacoustic (PA) infrared spectroscopy at the Canadian Light Source is described in this article. Aperture tests demonstrated an exponential relationship between the wavenumber where SR... more
The commissioning of synchrotron radiation (SR) photoacoustic (PA) infrared spectroscopy at the Canadian Light Source is described in this article. Aperture tests demonstrated an exponential relationship between the wavenumber where SR and thermal-source PA intensities are equal and beam diameter. Total PA intensity increased linearly with aperture size up to 1.5 mm (SR) or 3 mm (thermal source). At larger apertures, this intensity approached a limiting value. The SR beam diameter in the spectrometer was estimated to be about 0.8 mm in these tests. The low-frequency noise and dc offset that characterize SR PA spectra are suppressed through the calculation of average interferograms prior to Fourier transformation.
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A description of a coupled electrochemical and spectrometer interface using synchrotron infrared radiation is provided. The interface described allows for the precise and accurate timing needed for time-resolved IR spectroscopic studies... more
A description of a coupled electrochemical and spectrometer interface using synchrotron infrared radiation is provided. The interface described allows for the precise and accurate timing needed for time-resolved IR spectroscopic studies of electrochemical systems. The overall interface uses a series of transistor-transistor logic trigger signals generated from the commercial FTIR spectrometer to regulate the recording of control, electrochemical, and IR signals with reproducible and adjustable timing. The instrument has been tested using a thin-layer electrochemical cell with synchrotron light focused through microscope optics. The time-resolved response of the benzoquinone/dihydroxybenzoquinone redox couple is illustrated as an example of the instrument's capability.
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Research Interests: Engineering, Biocatalysis, Arabidopsis thaliana, Biological Sciences, Plant Physiology, and 15 morePlant, Arabidopsis, Enzyme, CHEMICAL SCIENCES, Mitochondrial dysfunction, Protein Secondary Structure Prediction, Seeds, NAD, Succinate Dehydrogenase, Carbon Partitioning, Embryo Development, Seed storage proteins, Globulins, Respiratory Rate, and phosphoenolpyruvate carboxylase
The result of interfacing step-scan spectroelectrochemistry with an IR microscope and synchrotron infrared (SIR) radiation is provided here. An external reflectance cell containing a 25 μm gold ultramicroelectrode is employed to achieve... more
The result of interfacing step-scan spectroelectrochemistry with an IR microscope and synchrotron infrared (SIR) radiation is provided here. An external reflectance cell containing a 25 μm gold ultramicroelectrode is employed to achieve an electrochemical time constant less than one microsecond. The use of a prototypical electrochemical system, i.e., the mass-transport controlled reduction of ferricyanide, allows for a proof of principle evaluation of the viability of SIR for step-scan spectroelectrochemistry. An analysis of the importance of accounting for synchrotron source variation over the prolonged duration of a step-scan experiment is provided. Modeling of the material flux in the restricted diffusion space afforded by the external reflectance cell allows the quantitative IR results to be compared to theoretical predictions. The results indicate that only at very short times does linear diffusion within the cavity dominate the electrode response and the majority of the transient signal operates under conditions of quasi-hemispherical diffusion. The analytical information provided by the IR signal is found to be considerably less than that derived from the current response due the latter's pronounced edge effects. The results provide a detection limit of 36 fmol for step-scan SIR measurements of ferrocyanide. Implications for future IR spectroelectrochemical studies in the microsecond domain are discussed.
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Synchrotron infrared radiation has been successfully coupled through an infrared (IR) microscope to a thin-cavity external reflectance cell to study the diffusion controlled redox of a ferrocyanide solution. Excellent signal-to-noise... more
Synchrotron infrared radiation has been successfully coupled through an infrared (IR) microscope to a thin-cavity external reflectance cell to study the diffusion controlled redox of a ferrocyanide solution. Excellent signal-to-noise ratios were achieved even at aperture settings close to the diffraction limit. Comparisons of noise levels as a function of aperture size demonstrate that this can be attributed to the high brilliance of synchrotron radiation relative to a conventional thermal source. Time resolved spectroscopic studies of diffusion controlled redox behavior have been measured and compared to purely electrochemical responses of the thin-cavity cell. Marked differences between the two measurements have been explained by analyzing diffusion in both the axial (linear) and radial dimensions. Whereas both terms contribute to the measured current and charge, only species that originate in the volume element above the electrode and diffuse in the direction perpendicular to the electrode surface are interrogated by IR radiation. Implications for the use of ultramicroelectrodes and synchrotron IR (SIR) to study electrochemical processes in the submillisecond time domain are discussed.