Fluorescence spectrometer for a single electrodynamically levitated microparticle

Arnold, Stephen; Folan, Lorcan M.

doi:10.1063/1.1138693

Cited by 109 publications

(47 citation statements)

References 14 publications

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“…Particles studied in this work were 20-to 30-/•m-diameter sulfuric acid droplets suspended in the quadrupole trap. The droplets are injected using a microparticle on-demand picopipette [Arnold and Folan, 1986]. As the particle is cooled down, a slow flow of nitrogen (100 cm 3 m -• STP) is passed through the quadrupole trap chamber.…”

Section: Experimental Methodsmentioning

confidence: 99%

Freezing behavior of single sulfuric acid aerosols suspended in a quadrupole trap

Carleton¹,

Sonnenfroh²,

Rawlins³

et al. 1997

J. Geophys. Res.

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Abstract. The freezing properties of sulfuric acid droplets were studied by suspending single 20-to 30-/am-diameter particles in a quadrupole trap and cooling them to stratospheric temperatures (-> 191.5 K). Each particle's dc balance voltage was measured to determine the particle composition as a function of temperature and map out the particle's trajectory relative to the sulfuric acid phase diagram. Angularly resolved optical scattering patterns were monitored to detect freezing events. Particles cooled through the sulfuric acid tetrahydrate region (35-70 wt % H2804) did not freeze and remained spherical liquid droplets for several hours. Only particles cooled through the ice-liquid equilibrium region (<35 wt % H2804) showed evidence of freezing. This supports previous experimental and field observations that stratospheric sulfuric acid aerosols are likely to remain liquid to within a few degrees of the ice frost point.

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Section: Experimental Methodsmentioning

confidence: 99%

Freezing behavior of single sulfuric acid aerosols suspended in a quadrupole trap

Carleton¹,

Sonnenfroh²,

Rawlins³

et al. 1997

J. Geophys. Res.

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“…The trap enables a charged particle (glycerol droplet) to be held stationary by a combination of ac and dc fields. While the dc field offsets the gravitational force, the ac field works with the trap's geometry to create a quasi-stable area in the central region [11][12][13]. The glycerol droplets are created by a grounded atomizer, and these droplets are passed through a conducting ring held at high voltage (∼800 V).…”

Section: Methodsmentioning

confidence: 99%

Quantitative Light-Scattering Angular Correlations of Conglomerate Particles

Pellegrino¹,

Videen²,

Pinnick³

1997

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Quantitative analyses were performed of the fluctuations in the light-scattering intensities associated with micrometer-size glycerol droplets containing spherical latex inclusions. Scattering intensities at two angles (the near-forward and near-backward directions) were measured as a function of time. We analyzed these signals using two techniques. We find that calculated autocorrelation time constants associated with these signals are not consistent with current models that are based on interference of light scattering from latex inclusions exhibiting Stokes-Einstein diffusion. The intensity fluctuations at different scattering angles display extended periods of both positive and negative correlations with characteristic time constants on the order of seconds. The time constants associated with the cross-correlations provide information on the physical parameters of the inclusions.

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“…EPTs have been used to perform Raman spectroscopy (Fung and Tang, 1989), Fourier transform infrared spectroscopy (Grader and Arnold, 1987), and fluorescence analysis from single suspended aerosols (Arnold and Folan, 1986). The extreme sensitivity of fluorescence measurements was demonstrated by Whitten et al (1991) who demonstrated single molecule detection in suspended particles.…”

Section: Experimental Single Particle Balance Backgroundmentioning

confidence: 99%

Measurements of the Ultraviolet Fluorescence Cross Sections and Spectra of Bacillus Anthracis Simulants

Stephens¹

1998

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Measurements of the ultraviolet autofluorescence spectra and absolute cross sections of the Bacillus anthracis (13a)simulants Bacillus globigii @g), Bacillus megaterium @m), Bacillus subtilis (Bs), and Bacillus cereus @c) were measured. Fluorescence spectra and cross sections of pine pollen (Pina echinata) were measured for comparison. Both dried vegetative cells and spores separated from the sporulated vegetative material were studied. The spectra were obtained by suspending a small number (< 10) of particles in air in our Single Particle Spectroscopy Apparatus (SPSA), illuminating the particles with light from a spectrally faltered arc lamp, and measuring the fluorescence spectra of the particles. The illumination was 280 nm (20 nm FWHM) and the fluorescence spectra was measured between 300 and 450 nm. The fluorescence cross section of vegetative Bg peaks at 320 nrn with a maximum cross section of 5 X 10"4 cm2/sr-nm-article while the Bg spore fluorescence peaks at310 nrn with peak fluorescence -1', 2 of 8 X 10 cm /sr-nrn-particle. Pine pollen particles showed a higher fluorescence peaking at 355 nm with a cross section of 1.7 X 10-'3cm2/sr-nm-particle. Integrated cross sections ranged from 3.0 X 10-'3for the Bg spores through 2.25 X 10-12(cm2/sr-particle) for the vegetative cells.

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Fluorescence spectrometer for a single electrodynamically levitated microparticle

Cited by 109 publications

References 14 publications

Freezing behavior of single sulfuric acid aerosols suspended in a quadrupole trap

Freezing behavior of single sulfuric acid aerosols suspended in a quadrupole trap

Quantitative Light-Scattering Angular Correlations of Conglomerate Particles

Measurements of the Ultraviolet Fluorescence Cross Sections and Spectra of Bacillus Anthracis Simulants

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