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Articles 1 - 22 of 22
Full-Text Articles in Social and Behavioral Sciences
Ultraviolet Photodissociation Action Spectroscopy Of Gas-Phase Protonated Quinoline And Isoquinoline Cations, Christopher Hansen, Stephen J. Blanksby, Adam J. Trevitt
Ultraviolet Photodissociation Action Spectroscopy Of Gas-Phase Protonated Quinoline And Isoquinoline Cations, Christopher Hansen, Stephen J. Blanksby, Adam J. Trevitt
Adam Trevitt
The gas-phase photodissociation action spectroscopy of protonated quinoline and isoquinoline cations (quinolineH+ and isoquinolineH+) is investigated at ambient temperature. Both isomers exhibit vibronic detail and wavelength-dependent photoproduct partitioning across two broad bands in the ultraviolet. Photodissociation action spectra are reported spanning 370-285 nm and 250-220 nm and analysed with the aid of electronic structure calculations: TD-DFT (CAM-B3LYP/aug-cc-pVDZ) is used for spectra simulations and CBS-QB3 for dissociation enthalpies. It is shown that the action spectra are afforded predominantly by two-photon excitation. The first band is attributed to both the S1 ← S0 and S2 ← S0 electronic transitions in quinolineH+, with …
Unimolecular Reaction Chemistry Of A Charge-Tagged Beta-Hydroxyperoxyl Radical, Sui So, Benjamin Kirk, Adam J. Trevitt, Uta Wille, Stephen J. Blanksby, Gabriel Da Silva
Unimolecular Reaction Chemistry Of A Charge-Tagged Beta-Hydroxyperoxyl Radical, Sui So, Benjamin Kirk, Adam J. Trevitt, Uta Wille, Stephen J. Blanksby, Gabriel Da Silva
Adam Trevitt
β-Hydroxyperoxyl radicals are formed during atmospheric oxidation of unsaturated volatile organic compounds such as isoprene. They are intermediates in the combustion of alcohols. In these environments the unimolecular isomerization and decomposition of β-hydroxyperoxyl radicals may be of importance, either through chemical or thermal activation. We have used ion-trap mass spectrometry to generate the distonic charge-tagged β-hydroxyalkyl radical anion, ˙CH2C(OH)(CH3)CH2C(O)O−, and investigated its subsequent reaction with O2 in the gas phase under conditions that are devoid of complicating radical-radical reactions. Quantum chemical calculations and master equation/RRKM theory modeling are used to rationalize the results and discern a reaction mechanism. Reaction is …
Ultraviolet Photodissociation Action Spectroscopy Of The N-Pyridinium Cation, Christopher Hansen, Stephen J. Blanksby, Nahid Chalyavi, Evan Bieske, Jeffrey R. Reimers, Adam J. Trevitt
Ultraviolet Photodissociation Action Spectroscopy Of The N-Pyridinium Cation, Christopher Hansen, Stephen J. Blanksby, Nahid Chalyavi, Evan Bieske, Jeffrey R. Reimers, Adam J. Trevitt
Adam Trevitt
The S1←S0 electronic transition of the N-pyridinium ion (C5H5NH+) is investigated using ultraviolet photodissociation (PD) spectroscopy of the bare ion and also the N2-tagged complex. Gas-phase N-pyridinium ions photodissociate by the loss of molecular hydrogen (H2) in the photon energy range 37 000-45 000 cm−1 with structurally diagnostic ion-molecule reactions identifying the 2-pyridinylium ion as the exclusive co-product. The photodissociation action spectra reveal vibronic details that, with the aid of electronic structure calculations, support the proposal that dissociation occurs through an intramolecular rearrangement on the ground electronic state following internal conversion. Quantum chemical calculations are used to analyze the measured …
Rapid Profiling Of Laser-Induced Photochemistry In Single Microdroplets Using Mass Spectrometry, Phillip J. Tracey, Bartholomew S. Vaughn, Brendon J. Roberts, Berwyck L. J Poad, Adam J. Trevitt
Rapid Profiling Of Laser-Induced Photochemistry In Single Microdroplets Using Mass Spectrometry, Phillip J. Tracey, Bartholomew S. Vaughn, Brendon J. Roberts, Berwyck L. J Poad, Adam J. Trevitt
Adam Trevitt
Rapid assessment of laser-induced photochemistry in single microdroplets is afforded by on-demand microdroplet generation coupled to a commercial ion-trap mass spectrometer. Single microdroplets (diameter 50 μm, 65 pL) fall on a steel needle held at +2 kV where they subsequently form a spray that is directed toward the inlet of an ion-trap mass spectrometer. It is demonstrated that single microdroplet mass spectra are recordable, one at a time, for methanol droplets containing 100 μM 4-iodoaniline. Extending on this, to probe laser-initiated photochemistry in single picoliter volumes, a UV laser pulse is timed to intercept the droplet before hitting the needle. …
Preparation Of An Ion With The Highest Calculated Proton Affinity: Ortho-Diethynylbenzene Dianion, Berwyck L. J Poad, Nicholas D. Reed, Christopher Hansen, Adam J. Trevitt, Stephen J. Blanksby, Emily G. Mackay, Michael S. Sherburn, Bun Chan, Leo Radom
Preparation Of An Ion With The Highest Calculated Proton Affinity: Ortho-Diethynylbenzene Dianion, Berwyck L. J Poad, Nicholas D. Reed, Christopher Hansen, Adam J. Trevitt, Stephen J. Blanksby, Emily G. Mackay, Michael S. Sherburn, Bun Chan, Leo Radom
Adam Trevitt
Owing to the increased proton affinity that results from additional negative charges, multiply-charged anions have been proposed as one route to prepare and access a range of new and powerful "superbases". Paradoxically, while the additional electrons in polyanions increase basicity they serve to diminish the electron binding energy and thus, it had been thought, hinder experimental synthesis. We report the synthesis and isolation of the ortho-diethynylbenzene dianion (ortho-DEB2−) and present observations of this novel species undergoing gas-phase proton-abstraction reactions. Using a theoretical model based on Marcus-Hush theory, we attribute the stability of ortho-DEB2− to the presence of a barrier that …
Product Branching Fractions Of The Ch + Propene Reaction From Synchrotron Photoionization Mass Spectrometry, Adam J. Trevitt, Matthew B. Prendergast, Fabien Goulay, John D. Savee, David L. Osborn, Craig A. Taatjes, Stephen R. Leone
Product Branching Fractions Of The Ch + Propene Reaction From Synchrotron Photoionization Mass Spectrometry, Adam J. Trevitt, Matthew B. Prendergast, Fabien Goulay, John D. Savee, David L. Osborn, Craig A. Taatjes, Stephen R. Leone
Adam Trevitt
The CH(X2Π) + propene reaction is studied in the gas phase at 298 K and 4 Torr (533.3 Pa) using VUV synchrotron photoionization mass spectrometry. The dominant product channel is the formation of C4H6 (m/z 54) + H. By fitting experimental photoionization spectra to measured spectra of known C4H6 isomers, the following relative branching fractions are obtained: 1,3-butadiene (0.63 ± 0.13), 1,2-butadiene (0.25 ± 0.05), and 1-butyne (0.12 ± 0.03) with no detectable contribution from 2-butyne. The CD + propene reaction is also studied and two product channels are observed that correspond to C4H6 (m/z 54) + D and C4H5D …
Radical Generation From The Gas-Phase Activation Of Ionized Lipid Ozonides, Shane R. Ellis, Huong T. Pham, Marc In Het Panhuis, Adam J. Trevitt, Todd W. Mitchell, Stephen J. Blanksby
Radical Generation From The Gas-Phase Activation Of Ionized Lipid Ozonides, Shane R. Ellis, Huong T. Pham, Marc In Het Panhuis, Adam J. Trevitt, Todd W. Mitchell, Stephen J. Blanksby
Adam Trevitt
Reaction products from the ozonolysis of unsaturated lipids at gas¿liquid interfaces have the potential to significantly influence the chemical and physical properties of organic aerosols in the atmosphere. In this study, the gas-phase dissociation behavior of lipid secondary ozonides is investigated using ion-trap mass spectrometry. Secondary ozonides were formed by reaction between a thin film of unsaturated lipids (fatty acid methyl esters or phospholipids) with ozone before being transferred to the gas phase as [M + Na]+ ions by electrospray ionization. Activation of the ionized ozonides was performed by either energetic collisions with helium buffer-gas or laser photolysis, with …
Photo And Collision Induced Isomerization Of A Cyclic Retinal Derivative: An Ion Mobility Study, Neville J. A Coughlan, Michael S. Scholz, Christopher Hansen, Adam J. Trevitt, Brian D. Adamson, Evan J. Bieske
Photo And Collision Induced Isomerization Of A Cyclic Retinal Derivative: An Ion Mobility Study, Neville J. A Coughlan, Michael S. Scholz, Christopher Hansen, Adam J. Trevitt, Brian D. Adamson, Evan J. Bieske
Adam Trevitt
A cationic degradation product, formed in solution from retinal Schiff base (RSB), is examined in the gas phase using ion mobility spectrometry, photoisomerization action spectroscopy, and collision induced dissociation (CID). The degradation product is found to be N-n-butyl-2-(β-ionylidene)-4-methylpyridinium (BIP) produced through 6π electrocyclization of RSB followed by protonation and loss of dihydrogen. Ion mobility measurements show that BIP exists as trans and cis isomers that can be interconverted through buffer gas collisions and by exposure to light, with a maximum response at λ = 420 nm.
Photodissociation Of Tempo-Modified Peptides: New Approaches To Radical-Directed Dissociation Of Biomolecules, David L. Marshall, Christopher S. Hansen, Adam J. Trevitt, Han Bin Oh, Stephen J. Blanksby
Photodissociation Of Tempo-Modified Peptides: New Approaches To Radical-Directed Dissociation Of Biomolecules, David L. Marshall, Christopher S. Hansen, Adam J. Trevitt, Han Bin Oh, Stephen J. Blanksby
Adam Trevitt
Radical-directed dissociation of gas phase ions is emerging as a powerful and complementary alternative to traditional tandem mass spectrometric techniques for biomolecular structural analysis. Previous studies have identified that coupling of 2-[(2,2,6,6-tetramethylpiperidin-1-oxyl)methyl]benzoic acid (TEMPO-Bz) to the N-terminus of a peptide introduces a labile oxygen–carbon bond that can be selectively activated upon collisional activation to produce a radical ion. Here we demonstrate that structurally-defined peptide radical ions can also be generated upon UV laser photodissociation of the same TEMPO-Bz derivatives in a linear ion-trap mass spectrometer. When subjected to further mass spectrometric analyses, the radical ions formed by a single laser …
Photoelectron Spectrum And Energetics Of The Meta-Xylylene Diradical, Mathias Steglich, Victoria Custodis, Adam J. Trevitt, Gabriel Da Silva, A Bodi, Patrick Hemberger
Photoelectron Spectrum And Energetics Of The Meta-Xylylene Diradical, Mathias Steglich, Victoria Custodis, Adam J. Trevitt, Gabriel Da Silva, A Bodi, Patrick Hemberger
Adam Trevitt
The meta-xylylene diradical m-C8H8 is a prototypical organic triplet that represents a building block for organic molecule-based magnets and also serves as a model compound for test and refinement of quantum chemical calculations. Flash vacuum pyrolysis of 1,3-bis-iodomethyl-benzene (m-C8H8I2) produces m-C 8 H 8 in gas phase; we used photoelectron spectroscopy to probe the first two electronic states of the radical cation, and resolve the vibrational fine structure of the ground state band. The determined adiabatic ionization energy of m-C8H8 is (7.27 ± 0.01) …
Observation Of Nondegenerate Cavity Modes For A Distorted Cavity Modes For A Distorted Polystyrene Microsphere, Adam J. Trevitt, Philip J. Wearne, Evan J. Bieske, Michael D. Schuder
Observation Of Nondegenerate Cavity Modes For A Distorted Cavity Modes For A Distorted Polystyrene Microsphere, Adam J. Trevitt, Philip J. Wearne, Evan J. Bieske, Michael D. Schuder
Adam Trevitt
Nondegenerate azimuthal morphology-dependent resonances are observed for a distorted, fluorescently labeled polystyrene microsphere levitated in a quadrupole ion trap. Modeling the individual resonances by using perturbation theory allows a determination of quadrupole and octupole distortion parameters. The particle’s shape changes slowly over the course of the measurement and eventually becomes spherical. The morphological changes are facilitated by laser heating of the particle above the polystyrene glass transition temperature. We demonstrate a method of transforming a trapped particle to a sphere and rendering its azimuthal modes degenerate.
Molecular Weight Growth In Titan's Atmosphere:Branching Pathways For The Reaction Of 1-Propynyl Radical (H3cc≡C˙) With Small Alkenes And Alkynes, Benjamin B. Kirk, John D. Savee, Adam J. Trevitt, David L. Osborn, Kevin R. Wilson
Molecular Weight Growth In Titan's Atmosphere:Branching Pathways For The Reaction Of 1-Propynyl Radical (H3cc≡C˙) With Small Alkenes And Alkynes, Benjamin B. Kirk, John D. Savee, Adam J. Trevitt, David L. Osborn, Kevin R. Wilson
Adam Trevitt
The reaction of small hydrocarbon radicals (i.e. ˙CN, ˙C2H) with trace alkenes and alkynes is believed to play an important role in molecular weight growth and ultimately the formation of Titan's characteristic haze. Current photochemical models of Titan's atmosphere largely assume hydrogen atom abstraction or unimolecular hydrogen elimination reactions dominate the mechanism, in contrast to recent experiments that reveal significant alkyl radical loss pathways during reaction of ethynyl radical (˙C2H) with alkenes and alkynes. In this study, the trend is explored for the case of a larger ethynyl radical analogue, the 1-propynyl radical (H3CC≡C˙), a likely product from the high-energy …
Insights Into Gas-Phase Reaction Mechanisms Of Small Carbon Radicals Using Isomer-Resolved Product Detection, Adam J. Trevitt, Fabien Goulay
Insights Into Gas-Phase Reaction Mechanisms Of Small Carbon Radicals Using Isomer-Resolved Product Detection, Adam J. Trevitt, Fabien Goulay
Adam Trevitt
For reactive gas-phase environments, including combustion, extraterrestrials atmospheres and our Earth's atmosphere, the availability of quality chemical data is essential for predictive chemical models. These data include reaction rate coefficients and product branching fractions. This perspective overviews recent isomer-resolved production detection experiments for reactions of two of the most reactive gas phase radicals, the CN and CH radicals, with a suite of small hydrocarbons. A particular focus is given to flow-tube experiments using synchrotron photoionization mass spectrometry. Coupled with computational studies and other experiment techniques, flow tube isomer-resolved product detection have provided significant mechanistic details of these radical + neutral …
Isomer-Specific Product Detection Of Gas-Phase Xylyl Radical Rearrangement And Decomposition Using Vuv Synchrotron Photoionization, Patrick Hemberger, Adam J. Trevitt, Thomas Gerber, Edward Ross, Gabriel Da Silva
Isomer-Specific Product Detection Of Gas-Phase Xylyl Radical Rearrangement And Decomposition Using Vuv Synchrotron Photoionization, Patrick Hemberger, Adam J. Trevitt, Thomas Gerber, Edward Ross, Gabriel Da Silva
Adam Trevitt
Xylyl radicals are intermediates in combustion processes since their parent molecules, xylenes, are present as fuel additives. In this study we report on the photoelectron spectra of the three isomeric xylyl radicals and the subsequent decomposition reactions of the o-xylyl radical, generated in a tubular reactor and probed by mass selected threshold photoelectron spectroscopy and VUV synchrotron radiation. Franck-Condon simulations are applied to augment the assignment of elusive species. Below 1000 K, o-xylyl radicals decompose by hydrogen atom loss to form closed-shell o-xylylene, which equilibrates with benzocyclobutene. At higher temperatures relevant to combustion engines, o-xylylene generates styrene in a multistep …
Formation And Stability Of Gas-Phase O-Benzoquinone From Oxidation Of Ortho-Hydroxyphenyl: A Combined Neutral And Distonic Radical Study, Matthew Prendergast, Benjamin B. Kirk, John D. Savee, David L. Osborn, Craig A. Taatjes, Kye Simeon Masters, Stephen J. Blanksby, Gabriel Da Silva, Adam J. Trevitt
Formation And Stability Of Gas-Phase O-Benzoquinone From Oxidation Of Ortho-Hydroxyphenyl: A Combined Neutral And Distonic Radical Study, Matthew Prendergast, Benjamin B. Kirk, John D. Savee, David L. Osborn, Craig A. Taatjes, Kye Simeon Masters, Stephen J. Blanksby, Gabriel Da Silva, Adam J. Trevitt
Adam Trevitt
Gas-phase product detection studies of o-hydroxyphenyl radical and O2 are reported at 373, 500, and 600 K, at 4 Torr (533.3 Pa), using VUV time-resolved synchrotron photoionisation mass spectrometry. The dominant products are assigned as o-benzoquinone (C6H4O2, m/z 108) and cyclopentadienone (C5H4O, m/z 80). It is concluded that cyclopentadienone forms as a secondary product from prompt decomposition of o-benzoquinone (and dissociative ionization of o-benzoquinone may contribute to the m/z 80 signal at photon energies ≳9.8 eV). Ion-trap reactions of the distonic o-hydroxyphenyl analogue, the 5-ammonium-2-hydroxyphenyl radical cation, with O2 are also reported and concur with the assignment of o-benzoquinone as …
Gas-Phase Oxidation Of The Protonated Uracil-5-Yl Radical Cation, James Bezzina, Matthew Prendergast, Stephen J. Blanksby, Adam J. Trevitt
Gas-Phase Oxidation Of The Protonated Uracil-5-Yl Radical Cation, James Bezzina, Matthew Prendergast, Stephen J. Blanksby, Adam J. Trevitt
Adam Trevitt
This study targets the kinetics and product detection of the gas-phase oxidation reaction of the protonated 5-dehydrouracil (uracil-5-yl) distonic radical cation using ion-trap mass spectrometry. Protonated 5-dehydrouracil radical ions (5-dehydrouracilH+ radical ion, m/z 112) are produced within an ion trap by laser photolysis of protonated 5-iodouracil. Storage of the 5-dehydrouracilH+ radical ion in the presence of controlled concentration of O2 reveals two main products. The major reaction product pathway is assigned as the formation of protonated 2-hydroxypyrimidine-4,5-dione (m/z 127) + •OH. A second product ion (m/z 99), putatively assigned as a five-member-ring ketone structure, is tentatively …
Hydroxyl Radical Formation In The Gas Phase Oxidation Of Distonic 2-Methylphenyl Radical Cations, Matthew Prendergast, Phillip A. Cooper, Benjamin B. Kirk, Gabriel Da Silva, Stephen J. Blanksby, Adam J. Trevitt
Hydroxyl Radical Formation In The Gas Phase Oxidation Of Distonic 2-Methylphenyl Radical Cations, Matthew Prendergast, Phillip A. Cooper, Benjamin B. Kirk, Gabriel Da Silva, Stephen J. Blanksby, Adam J. Trevitt
Adam Trevitt
The reactions of distonic 4-(N,N,N-trimethylammonium)-2-methylphenyl and 5-(N,N,N-trimethylammonium)-2-methylphenyl radical cations (m/z 149) with O 2 are studied in the gas phase using ion-trap mass spectrometry. Photodissociation (PD) of halogenated precursors gives rise to the target distonic charge-tagged methylphenyl radical whereas collision-induced dissociation (CID) is found to produce unreactive radical ions. The PD generated distonic radicals, however, react rapidly with O2 to form [M + O2]•+ and [M + O2 - OH]•+ ions, detected at m/z 181 and m/z 164, respectively. Quantum chemical calculations using G3SX(MP3) and M06-2X theories are deployed to examine key decomposition pathways of the 5-(N,N,N-trimethylammonium)-2-methylphenylperoxyl radical and rationalise …
Highly Efficient Gas-Phase Reactivity Of Protonated Pyridine Radicals With Propene, Cameron Bright, Matthew Prendergast, Patrick Kelly, James Bezzina, Stephen J. Blanksby, Gabriel Da Silva, Adam J. Trevitt
Highly Efficient Gas-Phase Reactivity Of Protonated Pyridine Radicals With Propene, Cameron Bright, Matthew Prendergast, Patrick Kelly, James Bezzina, Stephen J. Blanksby, Gabriel Da Silva, Adam J. Trevitt
Adam Trevitt
Small nitrogen containing heteroaromatics are fundamental building blocks for many biological molecules, including the DNA nucleotides. Pyridine, as a prototypical N-heteroaromatic, has been implicated in the chemical evolution of many extraterrestrial environments, including the atmosphere of Titan. This paper reports on the gas-phase ion-molecule reactions of the three dehydro-N-pyridinium radical cation isomers with propene. Photodissociation ion-trap mass spectrometry experiments are used to measure product branching ratios and reaction kinetics. Reaction efficiencies for 2-dehydro-N-pyridinium, 3-dehydro-N-pyridinium and 4-dehydro-N-pyridinium with propene are 70%, 47% and 41%, respectively. The m/z 106 channel is the major product channel across all cases and assigned 2-, 3-, …
Characterisation Of The Ionic Products Arising From Electron Photodetachment Of Simple Dicarboxylate Dianions, Benjamin B. Kirk, Adam J. Trevitt, Berwyck L. Poad, Stephen J. Blanksby
Characterisation Of The Ionic Products Arising From Electron Photodetachment Of Simple Dicarboxylate Dianions, Benjamin B. Kirk, Adam J. Trevitt, Berwyck L. Poad, Stephen J. Blanksby
Adam Trevitt
Much of what we currently understand about the structure and energetics of multiply charged anions in the gas phase is derived from the measurement of photoelectron spectra of simple dicarboxylate dianions. Here we have employed a modified linear ion-trap mass spectrometer to undertake complementary investigations of the ionic products resulting from laser-initiated electron photodetachment of two model dianions. Electron photodetachment (ePD) of the [M-2H]2- dianions formed from glutaric and adipic acid were found to result in a significant loss of ion signal overall, which is consistent with photoelectron studies that report the emission of slow secondary electrons (Xing et al., …
Are The Three Hydroxyphenyl Radical Isomers Created Equal? - The Role Of The Phenoxy Radical -, Patrick Hemberger, Gabriel Da Silva, Adam J. Trevitt, Thomas Gerber, A Bodi
Are The Three Hydroxyphenyl Radical Isomers Created Equal? - The Role Of The Phenoxy Radical -, Patrick Hemberger, Gabriel Da Silva, Adam J. Trevitt, Thomas Gerber, A Bodi
Adam Trevitt
We have investigated the thermal decomposition of the three hydroxyphenyl radicals (˙C6H4OH) in a heated microtubular reactor. Intermediates and products were identified isomer-selectively applying photoion mass-selected threshold photoelectron spectroscopy with vacuum ultraviolet synchrotron radiation. Similarly to the phenoxy radical (C6H5-O˙), hydroxyphenyl decomposition yields cyclopentadienyl (c-C5H5) radicals in a decarbonylation reaction at elevated temperatures. This finding suggests that all hydroxyphenyl isomers first rearrange to form phenoxy species, which subsequently decarbonylate, a mechanism which we also investigate computationally. Meta- and para-radicals were selectively produced and spectroscopically detectable, whereas the ortho isomer could not be traced due to its fast rethermalization and rapid …
Dissociation Of Proton-Bound Complexes Reveals Geometry And Arrangement Of Double Bonds In Unsaturated Lipids, Huong T. Pham, Matthew Prendergast, Christopher W. Dunstan, Adam J. Trevitt, Todd W. Mitchell, Ryan Julian, Stephen J. Blanksby
Dissociation Of Proton-Bound Complexes Reveals Geometry And Arrangement Of Double Bonds In Unsaturated Lipids, Huong T. Pham, Matthew Prendergast, Christopher W. Dunstan, Adam J. Trevitt, Todd W. Mitchell, Ryan Julian, Stephen J. Blanksby
Adam Trevitt
Double bond position and stereochemistry in unsaturated lipids can have profound impact on biological properties and activities but the assignment of these features by mass spectrometry is frequently challenging. Conventional techniques for lipid identification rely on collision-induced dissociation (CID) and are most often unable to differentiate between lipid isomers, particularly those involving double bond position and geometry (i.e., cis and trans). In this study, CID performed on proton-bound complexes of fatty acid methyl esters and iodoaniline (and related reagents) reveals unusual fragmentation patterns. CID products are shown to result from proton transfer and are associated with specific structures of the …
Drop-On-Demand Microdroplet Generation: A Very Stable Platform For Single-Droplet Experimentation, Bartholomew S. Vaughn, Phillip J. Tracey, Adam J. Trevitt
Drop-On-Demand Microdroplet Generation: A Very Stable Platform For Single-Droplet Experimentation, Bartholomew S. Vaughn, Phillip J. Tracey, Adam J. Trevitt
Adam Trevitt
This paper reports the performance of drop-on-demand piezo-activated microdroplet generation investigated using microdroplet cavity enhanced fluorescence spectroscopy. Aqueous microdroplets, doped with a fluorescent dye, exhibit fluorescence spectra that are dominated by cavity resonances (termed whispering gallery modes) that, when analysed using Mie theory, allow for the determination of the radius of each microdroplet. The effect of controlled changes in the square-wave droplet generator voltage waveform on droplet size is investigated as well as the size reproducibility of successive microdroplets. Furthermore, using custom square-wave waveforms, microdroplet radii spanning ∼10 to 30 μm are produced from the same droplet dispenser. These non-standard …