Aerodynamic Focusing of Nanoparticles: I. Guidelines for Designing Aerodynamic Lenses for Nanoparticles

Wang, Xiaoliang; Kruis, Frank Einar; McMurry, Peter H.

doi:10.1080/02786820500181901

Cited by 105 publications

(91 citation statements)

References 32 publications

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“…It consists of an aerodynamic lens system based on the design of Wang et al [9], a digitally-operated, gas-filled, quadrupole ion trap, endcap electrodes, and a detector system that incorporated a conversion dynode. The system was oriented in the vertical direction as depicted in the schematic so that the force of gravity acted along the axis of the quadrupole trap.…”

Section: Methodsmentioning

confidence: 99%

Trapping of intact, singly-charged, bovine serum albumin ions injected from the atmosphere with a 10-cm diameter, frequency-adjusted linear quadrupole ion trap

Koizumi

Whitten

Reilly

2008

J. Am. Soc. Mass Spectrom.

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High-resolution real-time particle mass measurements have not been achievable because the enormous amount of kinetic energy imparted to the particles upon expansion into vacuum competes with and overwhelms the forces applied to the charged particles within the mass spectrometer. It is possible to reduce the kinetic energy of a collimated particulate ion beam through collisions with a buffer gas while radially constraining their motion using a quadrupole guide or trap over a limited mass range. Controlling the pressure drop of the final expansion into a quadrupole trap permits a much broader mass range at the cost of sacrificing collimation. To achieve high-resolution mass analysis of massive particulate ions, an efficient trap with a large tolerance for radial divergence of the injected ions was developed that permits trapping a large range of ions for on-demand injection into an awaiting mass analyzer. The design specifications required that frequency of the trapping potential be adjustable to cover a large mass range and the trap radius be increased to increase the tolerance to divergent ion injection. The large-radius linear quadrupole ion trap was demonstrated by trapping singly-charged bovine serum albumin ions for on-demand injection into a mass analyzer. Additionally, this work demonstrates the ability to measure an electrophoretic mobility cross section (or ion mobility) of singly-charged intact proteins in the low-pressure regime. This work represents a large step toward the goal of high-resolution analysis of intact proteins, RNA, DNA, and viruses. (J Am Soc Mass Spectrom 2008, 19, 1942-1947) © 2008 Published by Elsevier Inc. on behalf of American Society for Mass Spectrometry E ver since the mass spectrometer was introduced, scientists have looked for ways to increase the mass range. The greatest advances came with the introduction of electrospray ionization (ESI) [1] and matrix-assisted laser desorption ionization (MALDI) [2]. These techniques permitted the production of massive ions in vacuum for subsequent mass analysis. Yet even with the advance of large ion production into the megadalton (MDa) range, the working range of mass spectrometers remained in the tens of kilodalton (kDa) range. The working range defines the range of mass-tocharge ratios where the spectrometer yields the most useful information; in other words, the range with the highest resolution, sensitivity, and mass accuracy.The working range limitation results from the kinetic energy imparted to the large ions during expansion into vacuum. Liu et al. [3] measured the centerline velocity of particles exiting their aerodynamic lens system through a 2-Torr expansion into vacuum. By extrapolating their results to zero particle diameter (mass), the kinetic energy of the particles traveling along the centerline of the expansion was found to be roughly linear yielding ϳ13.5, 85.3, and 530 eV for 10, 100, and 1000 kDa molecules. This result shows that even a lowpressure expansion can impart enough kinetic energy into large ions to compete ...

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Section: Methodsmentioning

confidence: 99%

Trapping of intact, singly-charged, bovine serum albumin ions injected from the atmosphere with a 10-cm diameter, frequency-adjusted linear quadrupole ion trap

Koizumi

Whitten

Reilly

2008

J. Am. Soc. Mass Spectrom.

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“…Understanding the transmission efficiency of these systems is important with respect to quantifying the overall performance of an aerosol mass spectrometer. Lens systems have been investigated via numerical calculations (Liu et al 1995a;Wang et al 2005a;2005b;Zhang et al 2002;, but few studies have focused on comparing the models to actual performance (Jayne et al 2000;Liu et al 1995b;Schreiner et al 1999;Tobias et al 2000). The work presented here compares model and measurement results and is motivated by the need to understand the efficiency of the lens system used on the Aerodyne Aerosol Mass Spectrometer (AMS) for quantifying aerosol particle measurements.…”

Section: Introductionmentioning

confidence: 99%

Transmission Efficiency of an Aerodynamic Focusing Lens System: Comparison of Model Calculations and Laboratory Measurements for the Aerodyne Aerosol Mass Spectrometer

Liu

Deng

Smith

et al. 2007

Aerosol Science and Technology

338

327

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The size-dependent particle transmission efficiency of the aerodynamic lens system used in the Aerodyne Aerosol Mass Spectrometer (AMS) was investigated with computational fluid dynamics (CFD) calculations and experimental measurements. The CFD calculations revealed that the entire lens system, including the aerodynamic lens itself, the critical orifice which defines the operating lens pressure, and a valve assembly, needs to be considered. Previous calculations considered only the aerodynamic lens. The calculations also investigated the effect of operating the lens system at two different sampling pressures, 7.8 × 10 4 Pa (585 torr) and 1.0 × 10 5 Pa (760 torr). Experimental measurements of transmission efficiency were performed with size-selected diethyl hexyl sebacate (DEHS), NH 4 NO 3 , and NaNO 3 particles on three different AMS instruments at two different ambient sampling pressures (7.8 × 10 4 Pa, 585 torr and 1.0 × 10 5 Pa, 760 torr). Comparisons of the measurements and the calculations show qualitative agreement, but there are significant deviations which are as yet unexplained. On the small size end (30 nm to 150 nm vacuum aerodynamic diameter), the measured transmission efficiency is lower than predicted. On the large size end (>350 nm vacuum aerodynamic diameter)

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“…The exit nozzle had an inner diameter of 1.85 mm and the barrel of the lens assembly was sealed by a system of double o-rings into the deposition chamber. Because our agglomerates were in a size regime where diffusion broadens the beam formed by the aerodynamic lenses, we selected helium as the carrier gas to lessen this effect (Wang et al 2005). Figure 4 demonstrates a sharp microtower that we deposited on a thin sapphire plate from agglomerates of CdSe/ ZnS FIG.…”

Section: Aerodynamic Focusing Of Nanocrystal Agglomeratesmentioning

confidence: 99%

Micropattern Deposition of Colloidal Semiconductor Nanocrystals by Aerodynamic Focusing

McMurry

Norris

et al. 2010

Aerosol Science and Technology

Self Cite

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We report the use of aerodynamic lenses to deposit micropatterns of colloidal semiconductor nanocrystals (or quantum dots). CdSe and CdSe/ZnS core/shell nanocrystals, with core diameters of 3.5-5 nm, were dispersed in hexane and then nebulized to generate agglomerates a few tens of nm in diameter, consisting of hundreds of nanocrystals. These agglomerates were then focused aerodynamically by a lens system. Microscale towers, lines, and patterns were deposited on thin sapphire plates and silicon wafers. The heights and widths of the deposits were adjustable by varying the experimental parameters. Line widths below 10 µm at fullwidth half-maximum are demonstrated. Upon exposure to near-UV illumination, these deposits exhibited robust fluorescence in the visible, with the color depending on the diameter of the individual nanocrystal cores. A red shift of the photoluminescence peaks from the nanocrystal dispersion to the glassy solid deposits was also observed, which confirmed that the deposits consist of closely packed nanocrystals embedded in the organic matrices. This approach, which is not restricted to semiconductor nanocrystals, provides an alternative means for the deposition of microscale patterns of colloidal nanoparticles.

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Aerodynamic Focusing of Nanoparticles: I. Guidelines for Designing Aerodynamic Lenses for Nanoparticles

Cited by 105 publications

References 32 publications

Trapping of intact, singly-charged, bovine serum albumin ions injected from the atmosphere with a 10-cm diameter, frequency-adjusted linear quadrupole ion trap

Trapping of intact, singly-charged, bovine serum albumin ions injected from the atmosphere with a 10-cm diameter, frequency-adjusted linear quadrupole ion trap

Transmission Efficiency of an Aerodynamic Focusing Lens System: Comparison of Model Calculations and Laboratory Measurements for the Aerodyne Aerosol Mass Spectrometer

Micropattern Deposition of Colloidal Semiconductor Nanocrystals by Aerodynamic Focusing

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