2. Construction and Characterisation of a Particle Magnifier
Helene Holmgren

3. Outline Background Condensation Particle Counter – CPC
Pulse Height Analysis - PHA
Particle Magnifier
Future Applications
Take Home Messages

4. Background Particle formation and growth Clusters - particle
Nanoparticles
Too small to scatter enough light to be detected by optical methods
Too small to carry significant charge to be classified according to electrical mobility
Diffusion losses

5. Condensation Particle Counter
2.5 – 1000 nm (TSI)
<10,000,000 particles cm-3 (TSI)
Measures particle number concentrations, but all information regarding size is lost

6. Condensation Particle Counter
Heated saturator
Vaporisation of working medium
Cooled condenser
Supersaturation
Condensation and growth
Optical detector
Light scattering

7. Condensation Particle Counter
S saturation ratio
P actual vapour partial-pressure (Pa)
P saturation vapour pressure (Pa)
g surface tension (N m-1)
M molecular weight (kg mol-1)
r density (kg m-3)
R universal gas constant (J K-1 mol-1)
T absolute temp (K)
d Kelvin diameter (m)

8. Pulse Height Analysis
Measures pulse heights produced when particles pass laser beam
Particles <15 nm (Saros et. al 1996)
Pulse height increases with particle size
Particles > 15 nm (Saros et. al 1996)
All particles grow to the same size

9. Particle Magnifier Detect, count AND size nanoparticles
Push size detection limit downwards
Optimise saturation and cooling systems
Find the most favourable working medium
Minimise diffusion losses
Instrument design

10. optical detection
condenser
saturator
particles

11. Particle Magnifier

12. Particle Magnifier Grimm Dust Monitor IR-laser Light-scattering
Pulse Height Analysis

13. Particle Magnifier

14. Future Applications Field measurements Laboratory studies
SOA formation
Terpenes emitted from vegetation
Laboratory studies
Connect to laminar flow tube (Emanuelsson)

15. Take Home Messages
It is possible to obtain number-size distributions of nanoparticles by combining the principles of CPCs with PHA technique
Particles <10 nm are activated at different sites in the condenser, and grow to different sizes
Particles >10 nm are activated near the entrance of the condenser, and grow to the same size

16. References
Saros, M., et al., Ultrafine aerosol measurement using a condensation nucleus counter with pulse height analysis. Aerosol Science and Technology, (2): p