Marc Garland's research while affiliated with Agency for Science, Technology and Research (A*STAR) and other places

Publications (137)

Article
We present a simple, bottom up method for the structural design of solid microparticles containing crystalline drug and excipient using microfluidic droplet-based processing. In a model system comprising 5-Methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (‘ROY’) as the drug and ethyl cellulose (‘EC’) as the excipient, we demonstrate a divers...
Article
Abstract Proteases are found deregulated in many diseases including cancer and neurodegenerative diseases. They thus represent good therapeutical targets for the development of inhibitors mainly small organic molecules. Peptide substrates containing fluorogenic groups constitute central tools for the monitoring of protease activities and inhibitor...
Chapter
In the context of metal-mediated organic synthesis, cooperativity and synergism are rather broad terms which are often used to denote systems where unusual rate or selectivity effects are observed. These effects can be exhibited by monometallic, heterobimetallic and even multimetallic systems. The present contribution looks exclusively at one of th...
Article
In situ spectroscopic studies of metal-mediated syntheses of new and previously unstudied systems are being increasingly used to better understand speciation and mechanistic aspects. These types of experiments give rise to an interesting question: namely, can one deduce from in situ data alone, and with no a priori chemical knowledge (i.e. chemical...
Article
A number of phenomenological reasons exist for synergism in mixed metal-mediated homogeneous catalysis. In the catalytic binuclear elimination reaction (CBER), the unusual high-activity system possesses mononuclear intermediates of each metal as well as dinuclear intermediates. All of these intermediates act in a synchronized and concerted manner t...
Article
Synthesis of 3-fluoro-2-hetarylindoles through addition of hetarenes to 3,3-difluoroindolium ions generated in situ by Zn(OTf)2-catalyzed oxazolidine ring opening is described. Indoles, pyrroles and alkyl-substituted furans can be used as hetaryl nucleophiles to afford a range of 3-fluoro-2-hetarylindole products 6 in 56–95 % yields. A diverse arra...
Article
Full-text available
This work systematically investigated the relationship between structure, morphology, photoelectrochemical (PEC) and photocatalytic (PC) properties of the TiO2 catalysts. A series of TiO2 catalysts with various phase compositions (anatase-, brookite- and finally rutile-rich samples) and morphologies (1D morphology, rhomboid nanoparticles (NPs) and...
Article
Full-text available
Two organic reactions, namely the reaction of cyclopentadiene (CPD) and dimethyl acetylene dicarboxylate (DMAD) and the dimerization reaction of CPD were conducted in toluene at 298.1 K at atmospheric pressure and measured by in situ FTIR spectroscopy. Band-target entropy minimization (BTEM) analyses were employed for obtaining the pure component s...
Article
Crystal structure determination is the key to a detailed understanding of crystalline materials and their properties. This requires either single crystals or high-quality single-phase powder X-ray diffraction data. The present contribution demonstrates a novel method to reconstruct single-phase powder diffraction data from diffraction patterns of m...
Article
Trace organometallic intermediates arising from complex organic syntheses are usually quite difficult to detect spectroscopically. In situ FTIR and in situ NMR are the only techniques that are used with any regularity for such studies. In this contribution, high-pressure in situ Raman spectroscopic measurements were performed for the rhodium cataly...
Article
Full-text available
The partial molar volumes, Vi, of the gas solutes H2, CO, and CO2, solvated in acetone, methanol, heptane, and diethylether are determined computationally in the limit of infinite dilution and standard conditions. Solutions are described with molecular dynamics simulations in combination with the OPLS-aa force field for solvents and customized forc...
Article
The rate of exchange of urea across the membranes of human erythrocytes (red blood cells) was quantified on the 1-s to 2-min timescale. (13)C-urea was hyperpolarized and subjected to rapid dissolution and the previously reported (partial) resolution of (13)C NMR resonances from the molecules inside and outside red blood cells in suspensions was obs...
Article
Reactions of Rh 2 (CO) 4 Cl 2 with two conjugated dienes, namely, 2,3-dimethyl-1,3-butadiene (DMBD) and isoprene, were performed in anhydrous hexane under argon atmosphere with multiple perturbations of reagents. These reactions were monitored by in-situ FTIR (FIR and MIR) and/or Raman spectroscopies and the collected spectra were further analyzed...
Article
In situ spectroscopic studies are increasingly used to better understand mechanistic aspects of homogeneous catalytic systems. In many cases, the raw measured spectra are simply inspected to identify new bands that appear under catalytic conditions. However, various types of advanced signal processing techniques can often provide considerably more...
Article
With the increasing use of microfluidics, there is a need for a rather general experimental approach in order to monitor and characterize transport effects. Indeed, micro-fabrication methods have allowed the inclusion of numerous new structures and devices within microfluidics channels, and such alterations in flow patterns should impact solute tra...
Article
The combined application of Raman microscopy and self‐modeling curve resolution techniques can address a wide range of material characterization problems. In particular, the combination of Raman microscopy and the Band‐Target Entropy Minimization (BTEM) algorithm has been applied to various organic, inorganic, pharmaceutical and bio‐material relate...
Article
Reactions of three alkynes, namely, 1-heptyne, 3-hexyne and 1-phenyl-1-butyne, with [Rh(4) (CO)(9) (μ-CO)(3) ] are performed in anhydrous hexane under argon atmosphere with multiple perturbations of alkynes and [Rh(4) (CO)(9) (μ-CO)(3) ]. The reactions are monitored by in situ UV/Vis spectroscopy, and the collected electronic spectra are further an...
Article
A robust heterogeneous self-supported chiral titanium cluster (SCTC) catalyst and its application in the enantioselective imine-cyanation/Strecker reaction is described under batch and continuous processes. One of the major hurdles in the asymmetric Strecker reaction is the lack of availability of efficient and reusable heterogeneous catalysts that...
Article
This work demonstrates a detailed process analytical technology (PAT) comparison study of dielectric constant measurement with turbidity measurement and focused beam reflectance measurement (FBRM) in detecting phase transitions during crystallization of three model solutions, namely stearic acid–ethyl acetate, paracetamol–ethanol and carbamazepine–...
Article
Metastable zone width, which can be approximated as the gap between the loci of cloud and clear points is an important control parameter for successful operations of solution crystallization processes. This study attempts to improve the accuracy of cloud point determination in paracetamol–ethanol solution using dielectric constant measurements and...
Article
The kinetics of the base-catalyzed reaction of methyl 4-hydroxybenzoate in aqueous-ethanol solvent medium was studied and analyzed via combined on-line transmission FTIR spectroscopy and Band-Target Entropy Minimization (BTEM) technique. This reaction is considered complex since it involves simultaneous hydrolysis and ethanolysis reactions of methy...
Article
Full-text available
Cyclopentene hydroformylation, both stoichiometric and catalytic, is performed starting with Rh4(CO)12 and CpW(CO)3H as precursors. Synergism is observed. Isotopic labeling experiments confirm 30% of the product formation occurs via a catalytic binuclear elimination reaction. Two new intermediates are spectroscopically identified using band target...
Article
A wide variety of digital filters exist for processing one-dimensional (1D) signals; however, the application of some filters results in pronounced systematic distortions in band shapes and band intensities. In the present contribution, filtering is achieved by optimization in which a general objective function is constructed that possesses a numbe...
Article
This study describes a method to determine the specific heat capacities of individual solids from multi-component solid mixtures. To achieve this end, powder X-ray diffraction measurements are used to provide information on the number and identity of constituents as well as their compositions while calorimetry measurements give the specific heat ca...
Article
Raman mapping measurements were performed on the glazed and unglazed surfaces of shards excavated from Yuan, Ming, and Qing dynasty strata. A number of areas on each surface were chosen. Circa 21 × 21 pixels were measured for each area using both 514 and 785-nm laser as the Raman excitation. Data were collected from 100–3600 cm−1. Many sets of spec...
Article
Full-text available
The inter-conversions of platinum carbonyl dianionic clusters, ([Pt(3)(CO)(6)](n)(2-), n = 2-5), have been studied in THF and acetonitrile using in situ FTIR spectroscopy. These inter-conversions were facilitated by the addition (or removal) of molecular hydrogen. The individual reactions, namely reductions and oxidations of [Pt(3)(CO)(6)](n)(2-) w...
Article
Full-text available
This contribution introduces the combined application of Raman microscopy and band-target entropy minimization (BTEM) in order to successfully reverse-engineer a multi-layer packaging material. Three layers are identified, namely, polyethylene, a paper and talc layer (with two distinct cellulose forms), and a poly-styrene co-polymer composite conta...
Article
Microabsorption may present a serious obstacle to performing accurate quantitative phase analysis by the Rietveld method for samples that contain phases with high X-ray absorption contrast. In this study, a multicomponent calibration approach is introduced to reduce the systematic bias that is not accounted for in conventional Rietveld analysis. In...
Article
Three different approaches for a total quantitative phase analysis of organic mixture data were presented and subsequently tested on a set of ten ternary powder mixtures consisting of �-glycine, �-lactose monohydrate and para- cetamol form I. In each of these methods, an external standard was used (in the present study, diamond) to determine the di...
Conference Paper
Metallized silicon (Si) nanowires are created by just by dipping the nanowires into an aqueous deposition solution for several minutes. Upon dipping into solution, metal ions were reduced and deposited on the top of the Si nanowire. Surface silicon oxide was simultaneously dissolved and removed by hydrogen fluoride (HF), so that the deposition reac...
Conference Paper
A SERS active substrate is fabricated based on well-ordered silicon nanostructure, using standard Si nanofabrication process technologies. This substrate has ordered silicon nanostructures with sharp edges and sub-100nm gaps followed by silver (30nm) and gold (15nm) deposition. These SERS substrates were measured using a InVia Raman microscope. Con...
Article
This study demonstrates the first use of a dielectric constant meter, coupled with an automated data logging module, for in situ monitoring of solution crystallization processes. The results show that this in situ measurement could detect not only the cloud point that corresponds to the onset of nucleation but also the clear point that closely repr...
Article
The binary solution of acetic acid in CDCl(3) was studied at room pressure on the interval T = 293-313 K with a series of acetic acid concentrations up to 0.16 M. In-situ Fourier transform infrared (FTIR) spectroscopy measurements on the interval of 400-3800 cm(-1) were utilized as the analytical method to monitor the spectral changes due to self-a...
Article
The present contribution reviews the operando spectroscopy programme in the area of homogeneous catalysis that exists at the Institute of Chemical and Engineering Sciences (ICES). This review first considers the importance of experimental design and then addresses a number of signal processing issues. Band-target entropy minimization (BTEM), an alg...
Article
Four aryl-substituted secondary phosphane oxides (SPOs) were tested as preligands in the rhodium catalyzed hydroformylation of cyclohexene and 1-octene. Three of them form active hydroformylation catalysts through their phosphinous acid tautomers. n-Regioselectivities of up to 56 % were achieved in the reaction with the linear olefin. The catalytic...
Article
Reactions of Rh2(CO)4Cl2 with 1,5-cyclooctadiene (COD) and tetramethylallene (TMA) were performed separately in anhydrous hexane under argon atmosphere. Multiple perturbations of Rh2(CO)4Cl2, COD and TMA were also performed during the reactions. These two reactions were monitored by in-situ FTIR (FIR and MIR) and/or Raman spectroscopies and the col...
Article
In the past decade, considerable progress has been made in the understanding of catalytic systems which simultaneously possess both mononuclear and dinuclear intermediates. The present contribution begins by reviewing the necessary background concerning stoichiometric binuclear elimination. This is followed by a summary of in situ FTIR studies on c...
Article
Raman spectroscopy with a fiber-optic probe was used to monitor the immobilized Candida antarctica lipase B (Novozym 435)-catalyzed esterification of oleic acid with ethanol in iso-octane as an organic solvent. The effects of reaction temperature and molar ratio of substrates were studied. An optimal reaction rate was found at 60°C, beyond which de...
Article
Full-text available
A novel analytical method to detect and characterize active pharmaceutical ingredient (API) trace crystallinity in an amorphous system using Raman microscopy and chemometric methods, namely band-target entropy minimization (BTEM) and target transformation factor analysis (TTFA) is developed. The method starts with Raman mapping measurements perform...
Article
Partially hydrolyzed titanium butoxide in combination with a chiral phenol ligand and TmsCN are employed as catalyst system for the title reaction.
Article
Differences in composition between the surface region and the bulk region for binary liquids can occur due to preferential adsorption, and such surface enrichment can influence mass and heat transport across the interface. In order to investigate surface enrichment, reliable methods for predicting surface compositions are required. In this study, a...
Article
The tautomeric behaviour of five secondary phosphane oxides (SPOs) with different electronic properties has been investigated by NMR and IR spectroscopy, density functional theory calculations and X-ray structural analysis. Proof is given that only with strong electron-withdrawing groups on the phosphorus atom can the relevant trivalent phosphinous...
Article
Hydroformylations of cyclopentene and 3,3-dimethylbut-1-ene were performed using both Rh(4)(CO)(12) and (eta(5)-C(5)H(5))Mo(CO)(3)H as precursors in n-hexane at 298 K. Both stoichiometric and catalytic hydroformylations were conducted as well as isotopic labeling experiments. Six organometallic pure component spectra were recovered from the high-pr...
Article
Raman spectra of human nail clippings from various sources were collected and then deconvoluted to obtain the pure component spectra of the underlying constituents present. This blind-deconvolution was performed using a self-modeling curve resolution technique, namely band-target entropy minimization (BTEM). The aim was to simplify the complexity o...
Article
This work demonstrates the utility of an online refractometer technique as a simple and accurate tool for monitoring the progress of a reaction and determining its end-point. It is also shown that, for a dilute reaction, the change of refractive index due to reaction is proportional to the extent of reaction. The corresponding kinetic rate coeffici...
Conference Paper
Homogeneous catalytic systems frequently contain intermediates of one and the same nuclearity. For example, many well known hydrogenation systems are believed to consist of mono-nuclear intermediates alone, and these species exist on one or more catalytic cycles. More complex catalytic cycles have been discussed in the literature. In particular, th...
Conference Paper
Highly reactive allenes are being increasingly used as reagents in complex organic syntheses, particularly in metal-mediated syntheses (both stoichiometric as well as homogeneous catalytic). Accordingly, a better understanding of the coordination chemistry of allenes with metal complexes is of interest. In order to understand some of the coordinati...
Article
In situ spectroscopic measurements of homogeneous catalytic reactions have become much more widely used. This is particularly true for FTIR, Raman, and NMR spectroscopic measurements. Although the instrumental and experimental advances have been quite noteworthy, less attention has been focused on the corresponding signal processing and numerical i...
Article
Combined on-line transmission FTIR spectroscopy and band-target entropy minimization (BTEM) analysis were employed in order to monitor and analyze the kinetics of the alkaline hydrolysis reaction of diethyl phthalate (DEP) in aqueous-ethanol solvent mixture. This reaction is irreversible and involves two consecutive steps with the formation of the...
Article
A simple method was demonstrated to metallize silicon (Si) nanowire (NW) just by dipping it into an aqueous deposition solution for several minutes. During the metallization process, metal ions were reduced and deposited on the top of the Si NW (where surface Si was oxidized). The surface silicon oxide was simultaneously dissolved and removed by hy...
Article
Simultaneous in situ/online spectroscopy and heat-flow measurements as well as multivariate analyses are performed, apparently for the first time, to determine heats of reaction for single and parallel reactions. Two different vibrational spectroscopy techniques, namely Raman and FTIR spectroscopy, are used in conjunction with flow-through TAM III...
Article
Full-text available
Heating (80 degrees C) the electron-precise, Sn-centred, icosahedral cluster [Rh(12)Sn(CO)(27)](4-) under a nitrogen atmosphere affords in sequence the electron-deficient icosahedral [Rh(12)Sn(CO)(26)](4-) and [Rh(12)Sn(CO)(25)](4-) derivatives. The reaction is reversible in solution and the parent compound is quantitatively regenerated upon exposu...
Article
The reaction of [C5H4(CH2)nX]Tl (1: n=2, X=NMe2, OMe, CN; n=3, X=NMe2) with [(η6-C6H6)RuCl(μ-Cl)]2, 2, afforded the sandwich compounds [{η5-C5H4(CH2)nX}Ru(η6-C6H6)]PF6, 3, and [η5-C5H4(CH2)nX]2Ru, 4. Photolytic cleavage of 3 in acetonitrile afforded the tethered products [{η5:κN-C5H4(CH2)nX}Ru(CH3CN)2]PF6, 5.
Article
Both nonreactive and reactive multiwell plate experiments were combined with Raman microscopy and band-target entropy minimization (BTEM) analysis. The multicomponent nonreactive experiments showed that accurate pure component spectral estimation is possible without recourse to any spectral libraries. The multicomponent reactive experiments showed...
Article
The solid-state reaction between ammonium heptamolybdate (AHM) and zirconium phosphate (ZrP) to give the ammonium salt of 12-molybdophosphoric acid (AMPA) was performed at 25-400 degrees C and monitored using in situ Raman spectroscopy. Spectral analysis of the Raman data using the band-target entropy minimization (BTEM) algorithm resulted in spect...
Article
In the present contribution, the biomimetic growth of carbonated hydroxyapatite (HA) on bioactive glass were investigated by Raman microscopy. Bioactive glass samples were immersed in simulated body fluid (SBF) buffered solution at pH 7.40 up to 17 days at 37 degrees C. Raman microscopy mapping was performed on the bioglass samples immersed in SBF...
Article
The BTEM family of algorithms, BTEM, tBTEM and MREM, were successfully applied to reconstruct the pure component spectra from broad and highly overlapping in-situ UV–Vis spectra. Ten spectra of cell plus water and dye solutions were collected in one semi-batch experiment. In this experiment multiple perturbations of three dyes, namely bromophenol b...
Conference Paper
The BTEM family of algorithms, BTEM [1], tBTEM [2] and MREM [3], were successfully applied to reconstruct the pure component spectra from in-situ FTIR spectra in a fast and accurate way. The reaction of Rh2(CO)4Cl2 with 1-pentyne was performed in anhydrous hexane under argon atmosphere. Multiple perturbations of Rh2(CO)4Cl2 and alkyne were also per...
Article
The molar heat capacities of chloroform, dichloromethane, methanol, acetonitrile, acetone, dimethyl sulfoxide, benzene, dimethylformamide, toluene, and cyclohexane, as well as their deuterated isotopologues, were measured using a multi-channel heat conduction TAM (Thermal Activity Monitor) III microcalorimeter. In addition, the apparent molar heat...
Article
A technique is demonstrated to detect DNA hybridization at low concentrations, based on Surface-Enhanced Raman Scattering (SERS) using silicon nanostructures coated with gold–silver as substrate. Standard silicon process technologies were employed to fabricate the SERS substrates featuring nanogaps with a characteristic distance of 15 ± 10 nm. Targ...
Article
Full-text available
The adsorption of NO and CO was studied on an alumina-supported palladium catalyst by in situ diffuse reflectance infrared spectroscopy (DRIFTS). The temperature range was 50-160 degrees C and a wide variety of partial pressures was used. The band-target entropy minimization (BTEM) algorithm was applied to the DRIFTS data sets resulting in the pure...
Article
Full-text available
The adsorption of NO and CO was studied on an alumina-supported platinum catalyst by in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). The temperature range was 50-160 degrees C and a wide variety of partial pressures was used. The band-target entropy minimization (BTEM) algorithm was applied to the DRIFTS data sets resu...
Article
Acetic acid can exist in many possible structural forms depending on its surrounding medium. A recently developed inverse problem methodology (J. Phys. Chem. B 2007, 111, 13064-13074) was utilized in order to elucidate acetic acid structures in a dilute nonpolar medium. In this regard, simultaneous and stopped-flow measurements of the bulk solution...
Article
Synergism has been previously observed in both rhodium-manganese- and rhodium-rhenium-catalyzed hydroformylation. Furthermore, detailed in situ spectroscopic investigations have conclusively shown that the phenomenological origin of this synergistic effect is catalytic binuclear elimination (J. Am. Chem. Soc. 2003, 125, 5540–5548; 2007, 129, 13327–...
Article
Two different organometallic ligand substitution reactions were investigated: (1) an achiral reactive system consisting of Rh(4)(CO)(12)+PPh(3)right harpoon over left harpoonRh(4)(CO)(11)PPh(3)+CO in n-hexane under argon; and (2) a chiral reactive system consisting of Rh(4)(CO)(12)+(S)-BINAPright harpoon over left harpoonRh(4)(CO)(10)BINAP+2CO in c...
Article
The deconvolution of multi-component mixtures in NMR spectroscopy is a challenging problem due to the spectral non-linearities. In the present contribution, two data sets were studied (A) 10 samples of a four-component non-reactive mixture measured with 1H, 13C, 19F, 31P NMR and (B) a three-solute cyclo-addition reaction measured with 13C NMR. Both...
Article
Raman microscopy was used in mapping mode to collect more than 1000 spectra in a 100 microm x 100 microm area from a commercial stamp. Band-target entropy minimization (BTEM) was then employed to unmix the mixture spectra in order to extract the pure component spectra of the samples. Three pure component spectral patterns with good signal-to-noise...
Article
The band-target entropy minimization method (BTEM) and its variant methods excel at reconstructing known/unknown pure spectra from mixtures without prior information. These mixtures may represent either non-reactive or even reactive systems. In this work, an unsupervised form of the entropy minimization curve resolution, namely, the multi-reconstru...
Article
In this paper, the use of in situ Raman spectroscopy together with a novel multivariate data analysis method, band-target entropy minimization (BTEM), is discussed to monitor the solution polymerization of methacrylamide in aqueous medium. Although FTIR spectroscopy is a more popular spectroscopic technique for polymer characterization and in situ...
Article
The combined application of two or more metals in homogeneous catalysis can lead to synergistic effects; however, the phenomenological basis for these observations often goes undetermined. The hetero-bimetallic catalytic binuclear elimination reaction, a system involving both mononuclear and dinuclear intermediates, has been repeatedly suggested as...
Article
A general inverse problem methodology is introduced to determine the partial molar polarizations and the dipole moments of individual solutes from multicomponent solutions alone. A model quaternary system consisting of three deuterated solutes, for example, acetone-d6, acetonitrile-d3, and dimethylformamide-d7 in cyclohexane at 298.15 K and 0.1013...
Article
A liquid-phase cycloaddition reaction near ambient temperature involving dimethyl acetylenedicarboxylate (DMAD) and cyclopentadiene (CP) as reactants was measured using a conventional Fourier transform infrared (FT-IR) spectrometer with an emission accessory. Two semi-batch experiments were performed and a total of 55 spectra were collected using a...
Article
Systematically arranged arrays of nanostructures were realized using CMOS compatible silicon technologies. The ordered arrays of nanostructures were formed using DUV photolithography, reactive ion etching and physical vapour deposition of silver. By varying the lithography dosage, arrays having different distance of closest approach between adjacen...
Article
Although infrared spectroscopy is a very common analytical tool in the chemical sciences, quantitative infrared spectroscopic studies of multi-component solutions (particularly on-line or in-line studies) have been hampered by the lack of a concise and robust numerical approach. Using an inert chemical species as internal standard, the usual absorb...
Article
A general methodology involving semi-batch experimental design is proposed in order to determine the volumetric standard states as well as homotactic and heterotactic volumetric solute–solute interaction coefficients from the associated quaternary solutions alone. The densities of quaternary aqueous solutions consisting of three alcohol solutes, e....
Article
Liquid-phase heterogeneous catalytic hydrogenation of 2-butanone over Pt/Al2O3 was performed in anhydrous d8-toluene with on-line FTIR measurements and further perturbations of water. The hydrogenation rates of both 2-butanone and solvent d8-toluene were strongly affected by the presence of water and unusual spectral changes were observed after the...
Article
Full-text available
Fourier transform Raman spectra of eight mixtures of four organic solids, namely dicyandiamide, melamine, acetamide and urea were measured. Matrices formed from these spectra were first subjected to singular value decomposition to obtain the right singular vectors. The right singular vectors were then subjected to blind source separation using band...
Article
A capacitance cell has been designed, constructed, and tested for stopped-flow measurements of very dilute low-relative permittivity liquid solutions. The capacitance cell utilizes a three-terminal design and is connected to ultrahigh sensitivity capacitance bridge. The cell was designed for operating conditions T = 243.15-373.15 K and P = 0-1 MPa...
Article
Pattern recognition in two-dimensional (2D) spectroscopy, without recourse to spectral libraries, etc., has a number of important potential applications. In the present contribution, two blind source separation techniques (spectral reconstruction) are applied to sets of 2D fluorescence data possessing both Rayleigh scattering and Raman scattering....
Article
Band-target entropy minimization (BTEM) was applied for the extraction of pure component Raman spectra from samples exhibiting a significant thermal background due to sample emission. In this method, singular value decomposition was first used to calculate the right singular vectors of the spectroscopic data matrix. Then the non-noise right singula...<