Design and performance characteristics of three continuous-flow condensation particle counters: a summary

Several modifications of the particle size magnifier (PSM) developed by Okuyama et al. have been introduced recently for detection of particles at diameters of 1 nm and below. However, their evaluation has been incomplete. Here we provide the first direct measurements of counting efficiencies near unity below 2 nm. We use the modified PSM described by Sgro and Fernández de la Mora, which separates thermally the PSM's original vapor generator from the water-cooled growth chamber by means of a narrow and short T where turbulent mixing with the aerosol takes place. The counting efficiency is seen to depend greatly on the aerosol flow, the amount of vapor, and temperature. With ethylene glycol vapor, under optimal conditions, the counting efficiency is 100% down to 1.6 nm (actual diameter of 1.2 nm), and negative particles are more easily activated than positive particles. The improved PSM is applied to the measurement of gold nanoparticle size distributions, and the results show it is a powerful aerosol detector for nanoparticles.

Section: Effect Of Charge Polarity On the Counting Efficiencysupporting

confidence: 84%

Performance Evaluation of an Improved Particle Size Magnifier (PSM) for Single Nanoparticle Detection

Kim

Okuyama

Mora

2003

“…The working principle of CPCs consists of three consecutive processes: supersaturating the aerosol with the vapor of a working fluid, growth of the particles by condensation of the supersaturated vapor on the particle surface and optical detection of the particles after their growth. Several methods can be used to generate the supersaturation: adiabatic expansion of an aerosol-vapor mixture (Metnieks and Pollak 1959), conductive cooling (Bricard et al 1976;Sem 2002) or heating (Hering et al 2005) and mixing of cool and warm saturated air flows (Kousaka et al 1982;Mavliev 2002;Wang et al 2002). In applications using CPCs a constant sample flow rate is desirable, which can be provided by the last three methods.…”

Section: Introductionmentioning

confidence: 99%

Particle Size Magnifier for Nano-CN Detection

Vanhanen

Mikkilä

Lehtipalo

et al. 2011

324

291

A new particle size magnifier (PSM) for detection of nano-CN as small as ∼1 nm in mobility diameter was developed, calibrated and tested in atmospheric measurements. The working principle of a PSM is to mix turbulently cooled sample flow with heated clean air flow saturated by the working fluid. This provides a high saturation ratio for the working fluid and activates the seed particles and grows them by condensation of the working fluid. In order to reach high saturation ratios, and thus to activate nano-CN without homogeneous nucleation, diethylene glycol was chosen as the working fluid. The PSM was able to grow nano-CN to mean diameter of 90 nm, after which an ordinary condensation particle counter was used to count the grown particles (TSI 3010). The stability of the PSM was found to be good making it suitable for stand-alone field measurements. Calibration results show that the detection efficiency of the prototype PSM + TSI 3010 for charged tetra-alkyl ammonium salt molecules having mobility equivalent diameters of 1.05, 1.47, 1.78, and 2.57 nm are 25, 32, 46, and 70%, respectively. The commercial version of the PSM (Airmodus A09) performed even better in the smallest sizes the detection efficiency being 51% for 1.47 nm and 67% for 1.78 nm.

“…A number of previous studies have sought to quantify the response of different instruments to, and uncertainty associated with measurement of, ultrafine PNSD and total particle number concentrations as a function of particle morphology, composition, and concentration for particular particle diameters (Sem 2002a;Liu et al 2006;Kulmala et al 2007;Mordas et al 2008;Giechaskiel et al 2012), often relative to a Faraday cup or electrometer detection system (Sem 2002b), and have illustrated some substantial variations between instruments. Many instrument intercomparison studies have focused on super-40-nm particles.…”

Section: Introductionmentioning

confidence: 99%

A Laboratory Comparison of Real-Time Measurement Methods for 10–100-nm Particle Size Distributions

Hornsby

Pryor

2014

We present information regarding the relative performance of five TSI particle sizing instruments when presented with several log-normally distributed particle populations that vary in terms of composition, concentration, and modal mean diameter (in the range of 10-100 nm) in a controlled laboratory environment. In experiments conducted with NaCl, NaNO 3 , and organic aerosols, across a total particle concentration suite ranging from approximately 1 × 10 4 cm −3 to 1 × 10 6 cm −3 , total number concentrations of sub-100-nm diameter particles from four SMPS systems and an FMPS all fall within ±50% of each other (and generally are within ±30%). However, larger discrepancies are evident in the particle size distribution, particularly for the NaCl particles, with an SMPS operated with a water-based CPC exhibiting large negative bias in modal peak concentrations relative to the isobutanol-based SMPS systems and the FMPS. Much closer agreement is found for NaNO 3 particles, although the SMPS systems tended to exhibit higher modal peak concentrations, and a slight shifting toward lower modal peak diameter than the FMPS.