Low Viscosity Solvents Research Articles

Ultrafast Excited-State Deactivation of the Bacterial Pigment Violacein.

The photophysical properties of the natural pigment violacein extracted from an Antarctic organism adapted to high exposure levels of UV radiation were measured in a combined steady-state and time-resolved spectroscopic study for the first time. In the low-viscosity solvents methanol and acetone, violacein exhibits low fluorescence quantum yields on the order of 1 × 10-4, and femtosecond transient absorption measurements reveal excited-state lifetimes of 3.2 ± 0.2 and 4.5 ± 0.2 ps in methanol and acetone, respectively. As solvent viscosity is increased, both the fluorescence quantum yield and excited-state lifetime of this intensely colored pigment increase dramatically, and stimulated emission decays 30-fold more slowly in glycerol than in methanol at room temperature. Excited-state deactivation is suggested to occur via a molecular-rotor mechanism in which torsion about an interring bond leads to a conical intersection with the ground state.

Ultrafast Excited-State Deactivation of the Bacterial Pigment Violacein.

The photophysical properties of the natural pigment violacein extracted from an Antarctic organism adapted to high exposure levels of UV radiation were measured in a combined steady-state and time-resolved spectroscopic study for the first time. In the low-viscosity solvents methanol and acetone, violacein exhibits low fluorescence quantum yields on the order of 10-4, and femtosecond transient absorption measurements reveal excited-state lifetimes of 3.2 ± 0.2 and 4.5 ± 0.2 picoseconds in methanol and acetone, respectively. As solvent viscosity is increased, both the fluorescence quantum yield and excited-state lifetime of this intensely colored pigment increase dramatically and stimulated emission decays 30-fold more slowly in glycerol than in methanol at room temperature. Excited-state deactivation is suggested to occur via a molecular-rotor mechanism in which torsion about an interring bond leads to a conical intersection with the ground state.

Optimization of normal phase chromatographic conditions for lipid analysis and comparison of associated detection techniques

One important challenge in lipid class analysis is to develop a method suitable or, at least adaptable, for a vast diversity of samples. In the current study, an improved normal-phase liquid chromatography (NPLC) method allowed analyzing the lipid classes present in mammalian, vegetable as well as microorganism (yeast and bacteria) lipid samples. The method effectively separated 30 lipid classes or subclasses with a special focus on medium polarity lipids. The separation was carried out with bare silica stationary phase and was coupled to evaporative light scattering detection (ELSD), charged aerosol detection (Corona-CAD®) and mass spectrometry. Solutions are provided to circumvent technical issues (such as pumping solvents of low viscosity, solvent purity, rinsing step). The influence of mobile phase composition and addition of ionic modifiers on the chromatographic behavior of particular lipid classes is documented. A comparison between ELSD and Corona-CAD® confirmed the interest of this later detector for samples with a wide range of concentration of different lipids. Three common atmospheric pressure ionization interfaces were used for coupling the NPLC separation to a LTQ Velos Pro® mass spectrometer. The comparison of the chromatographic profiles showed that atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) are both suitable to detect the different lipid classes whereas APPI allows a better sensitivity for lipids at low-concentration.

Composition Dependence of Relative Permittivities of Binary Solvent Mixtures

Binary solvent mixtures exist as liquids over a wide range of temperatures and pressures. For the rational use of the solvent mixtures it is essential to know their physical and chemical properties as functions of their composition and the ambience. The excess functions of physical constants (∆X sln E) can be represented in the polynomial form of the molar fraction (x 2) of the cosolvent by the empirical Redlich-Kister equation.The equation clearly satisfies the condition that ∆X sln E is zero at x 2 = 0 and at x 2= 1. The physical constants of solutions include relative static permittivity, refractive index, viscosity, vaper pressure, etc. The relative permittivity reflects the ease with which dielectric polarization proceeds. The relative permittivity is a measure of the solvent’s ability to insulate opposite charges from each other and has a very significant effect on the strength of the interactions between ions especially in dilute solutions. Electrostatic attractions and repulsions between ions are smaller in solvents with higher relative permittivities.We consider a binary solvent mixture containing molecules “1” and “2”. The numbers of the molecules “1” and “2” are N 1 and N 2, respectively. Assuming the tetrahedral quadruplets (ijkl) in a liquid state and the random distribution of the solvent molecules, we have derived the equation of the dependence of relative permittivity (ε r sln) on the composition of a binary solvent mixture. We obtained the coefficients (ai ) of the relative permittivities in the Redlich-Kister equation. a 0 is a dominant factor governing ∆X sln E. a 0 may reflect the difference in the cooperative orientation polarization between the same and different types of dipoles. a 1 and a 2 may represent the difference in the contribution of the two components to the cooperative orientation polarization.We investigated the relative permittivities (ε r sln) and excess relative permittivities (∆ε r sln E) of binary mixtures of ethylene carbonate (EC) and linear carbonate as a function of the composition at 25 ºC. The symbol x 2 denotes the molar fraction of a low-viscosity solvent: 2-fluoroethyl methyl carbonate (2FEMC) or ethyl methyl carbonate (EMC). EC is a cyclic carbonate, whereas 2FEMC and EMC are linear carbonates. EC and EMC are commonly used as high-polarity and low-viscosity solvents, respectively, for lithium-ion batteries.The equations of the composition dependence of ε r sln and ∆ε r sln E fitted experimental data. The ε r sln of the EC−2FEMC binary mixture was higher than that of the EC−EMC counterpart. The value of a 0 found in the EC−2FEMC binary solvent system (−49) was less negative than that in the EC−EMC binary solvent system (−51). These findings suggest that the amount of the cooperative orientation polarization of the EC−2FEMC binary mixture is larger than that found for the EC−EMC counterpart. The attraction between EC and 2FEMC molecules can be based on nonconventional weak intermolecular hydrogen bonding (CF−H···O or C−H···F−C). The weak hydrogen-bonding system does not exchange its proton and therefore it is no more a genuine hydrogen bond; it is an electrostatic attraction between positive charge on the hydrogen and negative charge on the organic fluorine or the organic oxygen.

Towards Overhauser DNP in supercritical CO2

Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for 1H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in 1H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2–4ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4T on high pressure superheated water and model systems such as toluene in high pressure CO2.

Multigrid MALDI mass spectrometry imaging (mMALDI MSI).

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is an important technique for the spatially resolved molecular analysis of tissue sections. The selection of matrices influences the resulting mass spectra to a high degree. For extensive and simultaneous analysis, the application of different matrices to one tissue sample is desirable. To date, only a single matrix could be applied to a tissue section per experiment. However, repetitive removal of the matrix makes this approach time-consuming and damaging to tissue samples. To overcome these drawbacks, we developed a multigrid MALDI MSI technique (mMALDI MSI) that relies on automated inkjet printing to place differing matrices onto predefined dot grids. We used a cooled printhead to prevent cavitation of low viscosity solvents in the printhead nozzle. Improved spatial resolution of the dot grids was achieved by using a triple-pulse procedure that reduced droplet volume. The matrices can either be applied directly to the thaw-mounted tissue sample or by precoating the slide followed by mounting of the tissue sample. During the MALDI imaging process, we were able to precisely target different matrix point grids with the laser to simultaneously produce distinct mass spectra. Unlike the standard method, the prespotting approach optimizes the spectra quality, avoids analyte delocalization, and enables subsequent hematoxylin and eosin (H&E) staining. Graphical Abstract Scheme of the pre-spotted multigrid MALDI MSI workflow.

Liquid carbon dioxide-based coating of a uniform carbon layer on hierarchical porous MoO2 microspheres and assessment of their electrochemical performance

Hierarchical mesoporous MoO2 microspheres coated with a uniform and ultrathin carbon layer were synthesized via a supercritical methanol (scMeOH) route followed by high-pressure free-meniscus coating (hFMC) using liquid carbon dioxide (l-CO2) as a coating solution. The MoO2 particles synthesized in scMeOH without surfactants or structure-directing chemicals exhibited nanosized primary particles of 30–80nm diameter, whose loose aggregation produced microsized secondary particles of 0.5–4.8μm diameter. The MoO2 particles had a highly porous structure with an average pore diameter of 10.5nm and a porosity of 52.7%. An ultrathin, uniform, and conformal carbon layer with thickness in the range of 1.5–2.0nm was coated on the primary MoO2 particles using l-CO2 as low-viscosity and low-surface tension solvent. When tested as anode in lithium ion batteries, the carbon-coated, hierarchical porous MoO2 (C-MoO2) particles exhibited excellent electrochemical performance. C-MoO2 with a carbon content of 6.6wt% delivered a reversible discharge capacity of 451.5mAhg−1 at 83.8mAg−1 after 100 cycles. C-MoO2 with a carbon content of 14.1wt% exhibited 120.9mAhg−1 of discharge capacity at the fast charge–discharge current of 3352mAg−1. The enhanced electrochemical performance of C-MoO2 was attributed to enhanced charge transfer kinetics to the electrode surface and increased Li ion diffusivity to the MoO2 phase during the charge/discharge process, as confirmed by electrochemical impedance spectroscopy.

Study on the Removal of Metals from Pyrolysis Oil with Ion-Exchange Resins at Ambient Conditions

An ion-exchange process for removal of metals from liquid pyrolysis oil at ambient temperature has been developed. Pyrolysis oil is first blended with a polar and low-viscosity organic solvent or a solvent mixture to adjust its kinematic viscosity to about 60 mm2/s or less. The blended oil is then treated with strongly acidic ion-exchange resin. The metal content in the treated oil can be reduced to 5 ppm or less. The equilibrium isotherm and kinetic studies indicate that the exchange is a pseudo-first-order process. The rate order observed is Na+ > K+ > Mg2+ > Ca2+ ≫ Fe3+.

Longitudinal hypersound in solutions of a viscous liquid in a low-viscosity one

The results of measurements of the hypersound velocity and absorbtion by Mandelstam—Brillouin spectra in aqueous solutions of glycerin in a wide temperature (viscosity) range are presented. It is shown that the experimental results are well described by formulas of the Isakovich—Chaban nonlocal theory based on the assumption about the two-component structure of a viscous liquid containing clusters with sharp boundaries, “floating” in a disordered liquid. In the experiment, the viscous component concentration in a low-viscosity medium was varied, which corresponded to cluster concentration variations in it. It was shown that clusters are stable structures. The number of clusters decreases as a low-viscosity solvent is added, while their size remains unchanged.

Mathematical Modeling Of Radio-Frequency Electromagnetic And Acoustic Impact On Formation In Combination With Solvent Injection

We investigate the possibility of increasing the efficiency of extraction of high-viscosity oil combined effect of radio-frequency (RF) electromagnetic (EM) and acoustic fields on the formation and miscible displacement oil solvent. A mathematical model of two-stage impact on the oil reservoir. At the 1st stage, the heating of the formation RF electromagnetic and acoustic field. At the 2nd stage the RF heating of the formation with simultaneous injection of low-viscosity solvent.

Menthol-based Eutectic Mixtures: Hydrophobic Low Viscosity Solvents

Inspired by one of the major problems in the pharmaceutical industry, we advantageously used the formation of eutectic mixtures to synthesize new solvents. The aim of this work is to identify low viscosity, cheap, biodegradable and hydrophobic eutectic solvents from natural resources. Consequently, novel eutectic mixtures based on dl-menthol and naturally occurring acids, namely pyruvic acid, acetic acid, l-lactic acid, and lauric acid, were synthesized and are here reported for the first time. The obtained dl-menthol-based eutectic mixtures were analyzed using NMR and FTIR spectroscopy in order to check their structures and purities and to confirm the interaction of the two compounds leading to the eutectic formation. Important solvent thermophysical properties, such as density and viscosity, of the prepared eutectic solvents with different water contents (dried and water-saturated) were measured. Finally, taking advantage of their hydrophobic character, namely the formation of two phases with water at r...

A Combined Experimental and Molecular Dynamics Study of Iodide-Based Ionic Liquid and Water Mixtures.

Iodide-based ionic liquids have been widely employed as iodide sources in electrolytes for applications utilizing the triiodide/iodide redox couple. While adding a low-viscosity solvent such as water to ionic liquids can greatly enhance their usefulness, mixtures of highly viscous iodide-containing ILs with water have never been studied. This paper investigates, for the first time, mixtures of water and the ionic liquid 1-butyl-3-methylimidazolium iodide ([BMIM][I]) through a combined experimental and molecular dynamics study. The density, melting point, viscosity, and conductivity of these mixtures were measured by experiment. The composition region below 50% water by mole was found to differ dramatically from the region above 50% water, with trends in density and melting point differing before and after that point. Water was found to have a profound effect on viscosity and conductivity of the IL, and the effect of hydrogen bonding was discussed. Molecular dynamics simulations representing the same mixture compositions were performed. Molecular ordering was observed, as were changes in this ordering corresponding to water content. Molecular ordering was related to the experimentally measured mixture properties, providing a possible explanation for the two distinct composition regions identified by experiment.

Analysis of drop deformation dynamics in turbulent flow

Drop breakage and coalescence influence the particle formation in liquid–liquid dispersions. In order to reduce the influencing factors of the whole dispersion process, single drops where coalescence processes can be neglected were analyzed in this work. Drops passing the turbulent vicinity of a single stirrer blade were investigated by high-speed imaging. In order to gain a statistically relevant amount of drops passing the area of interest and corresponding breakage events, at least 1600 droplets were considered for each parameter set of this work. A specially developed fully automatic image analysis based on Matlab® was used for the evaluation of the resulting high amount of image data. This allowed the elimination of the time-consuming manual analysis and furthermore, allowed the objective evaluation of the drops' behavior. Different deformation parameters were considered in order to describe the drop deformation dynamics properly. Regarding the ratio of both main particle axes (θaxes), which was therefore approximated through an ellipse, allowed the determination of very small deviations from the spherical shape. The perimeter of the particle (θperi) was used for the description of highly deformed shapes. In this work the results of a higher viscosity paraffin oil (ηd=127mPa·s) and a low viscosity solvent (petroleum, ηd=1.7mPa·s) are presented with and without the addition of SDS to the continuous water phase. All results show that the experimentally determined oscillation but also deformation times underlie a wide spreading. Drop deformations significantly increased not only with increasing droplet viscosity, but also with decreasing interfacial tension. Highly deformed particles of one droplet species were more likely to break than more or less spherical particles. As droplet fragmentation results from a variety of different macro-scale deformed particles, it is not assumed that a critical deformation value must be reached for the fragmentation process to occur. Especially for highly deformed particles thin particle filaments are assumed to induce the breakage process and, therefore, be responsible for the separation of drops.

Speed of Conformational Change: Comparing Explicit and Implicit Solvent Molecular Dynamics Simulations

Adequate sampling of conformation space remains challenging in atomistic simulations, especially if the solvent is treated explicitly. Implicit-solvent simulations can speed up conformational sampling significantly. We compare the speed of conformational sampling between two commonly used methods of each class: the explicit-solvent particle mesh Ewald (PME) with TIP3P water model and a popular generalized Born (GB) implicit-solvent model, as implemented in the AMBER package. We systematically investigate small (dihedral angle flips in a protein), large (nucleosome tail collapse and DNA unwrapping), and mixed (folding of a miniprotein) conformational changes, with nominal simulation times ranging from nanoseconds to microseconds depending on system size. The speedups in conformational sampling for GB relative to PME simulations, are highly system- and problem-dependent. Where the simulation temperatures for PME and GB are the same, the corresponding speedups are approximately onefold (small conformational changes), between ∼1- and ∼100-fold (large changes), and approximately sevenfold (mixed case). The effects of temperature on speedup and free-energy landscapes, which may differ substantially between the solvent models, are discussed in detail for the case of miniprotein folding. In addition to speeding up conformational sampling, due to algorithmic differences, the implicit solvent model can be computationally faster for small systems or slower for large systems, depending on the number of solute and solvent atoms. For the conformational changes considered here, the combined speedups are approximately twofold, ∼1- to 60-fold, and ∼50-fold, respectively, in the low solvent viscosity regime afforded by the implicit solvent. For all the systems studied, 1) conformational sampling speedup increases as Langevin collision frequency (effective viscosity) decreases; and 2) conformational sampling speedup is mainly due to reduction in solvent viscosity rather than possible differences in free-energy landscapes between the solvent models.

Chemical and Physical Absorption of SO2 by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Sulfur dioxide (SO2) removal is a key component of many industrial processes, especially coal-fired power generation. Controlling SO2 emissions is vital to maintaining environmental quality, as SO2 is a contributor to acid rain, but has value as a chemical feedstock. Although a number of novel solvents/materials including ionic liquids (ILs) have recently been proposed for alternatives to limestone scrubbing for SO2 capture/removal from point sources, the imidazole architecture presents a convenient, inexpensive and efficient class of low volatility and low viscosity solvents to accomplish this goal. On the basis of our prior work with imidazoles for CO2 capture, we have extended our interests toward understanding the relationship between imidazole structure and SO2 absorption. Using a series of imidazole compounds with various substituents at the 1, 2 and/or 4(5) positions of the five-membered ring, SO2 absorption via both chemical and physical mechanisms was observed. The chemical absorption product is ...

Excited-state proton and charge transfer in protonated amino and methylated derivatives of 2-(2'-hydroxyphenyl)benzimidazole.

We studied the excited-state behavior of a family of mono- and diprotonated derivatives of 2-phenylbenzimidazole in different solvents, using steady-state and time-resolved fluorescence spectroscopy. The species investigated were 2-(4'-amino-2'-hydroxyphenyl)benzimidazole (1), the diethylamino analogue 2-(4'-N,N-diethylamino-2'-hydroxyphenyl)benzimidazole (2) and its N-methylated derivative 1-methyl-2-(4'-N,N-diethylamino-2'-hydroxyphenyl)benzimidazole (3). The O-methoxy derivatives of 2 and 3 (2-OMe and 3-OMe), and the simpler models 2-phenylbenzimidazole (4) and its 4'-amino (5) and 4'-dimethylamino (6) derivatives were also studied. We found that the dications of 1, 2, and 3 (protonated at the benzimidazole N3 and at the amino group) were strong photoacids, which were deprotonated at the hydroxyl group upon excitation in aqueous solution (totally for 2 and 3) to give a tautomer of the ground-state monocation. In contrast, no photodissociation was observed for the monocations of these species. Instead, some of the monocations studied behaved as molecular rotors, for which electronic excitation led to a twisted intramolecular charge transfer (TICT) state. The monocations of 2, 3, 2-OMe, 3-OMe, and 6, protonated at the benzimidazole N3, experienced a polarity- and viscosity-dependent radiationless deactivation associated with a large-amplitude rotational motion. We propose that this process is connected to an intramolecular charge transfer from the dimethylaminophenyl or diethylaminophenyl moiety (donor) to the protonated benzimidazole group (acceptor) of the excited monocation, which yields a twisted charge-transfer species. No fluorescence from this species was detected except for 3 and 3-OMe in low-viscosity solvents.

Reverse Micelles As a Platform for Dynamic Nuclear Polarization in Solution NMR of Proteins

Despite tremendous advances in recent years, solution NMR remains fundamentally restricted due to its inherent insensitivity. Dynamic nuclear polarization (DNP) potentially offers significant improvements in this respect. The basic DNP strategy is to irradiate the EPR transitions of a stable radical and transfer this nonequilibrium polarization to the hydrogen spins of water, which will in turn transfer polarization to the hydrogens of the macromolecule. Unfortunately, these EPR transitions lie in the microwave range of the electromagnetic spectrum where bulk water absorbs strongly, often resulting in catastrophic heating. Furthermore, the residence times of water on the surface of the protein in bulk solution are generally too short for efficient transfer of polarization. Here we take advantage of the properties of solutions of encapsulated proteins dissolved in low viscosity solvents to implement DNP in liquids. Such samples are largely transparent to the microwave frequencies required and thereby avoid significant heating. Nitroxide radicals are introduced into the reverse micelle system in three ways: attached to the protein, embedded in the reverse micelle shell, and free in the aqueous core. Significant enhancements of the water resonance ranging up to ∼−93 at 0.35 T were observed. We also find that the hydration properties of encapsulated proteins allow for efficient polarization transfer from water to the protein. These and other observations suggest that merging reverse micelle encapsulation technology with DNP offers a route to a significant increase in the sensitivity of solution NMR spectroscopy of proteins and other biomolecules.

Characterization of trans-2-[4-[(Dimethylamino)styryl]benzothiazole as an Ultrafast Isomerization Probe and a Modifed Kramers Theory Analysis

The photophysics of trans-2-[4-(dimethylamino)styryl]benzothiazole (DMASBT) was investigated by electronic structure calculations and steady-state and time-resolved emission spectroscopy in a wide range of solvents, including temperature and pressure dependence. DMASBT undergoes a facile photoinduced trans-cis isomerization similar to the reaction of trans-stilbene. The cis isomer has a lifetime of ∼1 ps and does not contribute appreciably to the steady-state emission spectrum. The absorption spectrum of the cis form overlaps that of the trans form such that considerable care is needed in determining correct emission quantum yields. The approximate equality of absorption and emission transition moments of DMASBT in all solvents indicates that absorption and emission involve a single excited state with high radiative rate. The low quantum yields of DMASBT in low-viscosity solvents reflect emission lifetimes in the 20-50 ps range. The nonradiative rates of DMASBT, which are assumed to measure the rate of isomerization in S1, depend upon both solvent viscosity and polarity. A modified Kramers analysis, which allows for a polarity-dependent barrier height, provides a satisfactory description of these rates but only if it is assumed that friction in alcohol solvents is more weakly dependent upon viscosity than in other types of solvents.

Interfacial Characteristics of a PEGylated Imidazolium Bistriflamide Ionic Liquid Electrolyte at a Lithium Ion Battery Cathode of LiMn2O4

Nonvolatile and nonflammable ionic liquids (ILs) have distinct thermal advantages over the traditional organic solvent electrolytes of lithium ion batteries. However, this beneficial feature of ILs is often counterbalanced by their high viscosity (a limiting factor for ionic conductivity) and, sometimes, by their unsuitable electrochemistry for generating protective layers on electrode surfaces. In an effort to alleviate these limiting aspects of ILs, we have synthesized a PEGylated imidazolium bis(trifluoromethylsulfonyl)amide (bistriflamide) IL that exhibited better thermal and electrochemical stability than a conventional electrolyte based on a blend of ethylene carbonate and diethyl carbonate. The electrochemical performance of this IL has been demonstrated using a cathode consisting of ball-milled LiMn2O4 particles. A direct comparison of the ionic liquid electrolyte with the nonionic low-viscosity conventional solvent blend is presented.

Design of the dye cell of a dye laser to facilitate repetitive operation in the single longitudinal mode

A dye cell was designed and fabricated to facilitate high repetition rate single longitudinal mode (SLM) operation with low viscosity solvents such as ethanol. The flow circulation (vortex) in the dye cell was eliminated by reducing the flow cross section from 10 to 5 mm2 with optimized flow entry. The physical dimension of dye cell is very important for short cavity SLM lasers in terms of keeping the cavity length small. Flow visualization of various geometries in the dye cell was carried out using commercial computational fluid dynamics (CFD) software. It was found that the slit as well as tubular entry to the dye cell of cross section 1 × 10 mm2 shows flow circulation (a vortex) near the entry to the dye cell. The SLM was obtained from a 10 mm2 flow cross section dye cell with a high viscosity solvent such as binary solvent (200 cP) or glycerol (1400 cP) with a higher bandwidth. The pulse to pulse fluctuations in the bandwidth and wavelength are generally associated with dye flow instabilities. These flow related instabilities reduced with higher viscosity solvents, which results in an increased bandwidth of the SLM dye laser (by nearly 40%). A specially designed dye cell was fabricated and used for SLM operation at two different pump lasers having different pulse repetition rates ranging from 20 to 6000 Hz. SLM operation was demonstrated for longitudinal pumping of the dye cell with low viscosity solvents. Time averaged SLM line widths of 400 and 175 MHz were obtained with a copper vapor laser (CVL) and Nd:YAG laser, respectively. A single pulse line width of 315 MHz was obtained with a CVL pumped dye laser.