Measurement comparison between light absorption of 300nm Car-O-Jet aerosols at 1064nm from a near-IR DPAS device at 1064nm and particle number concentrations from a TSI CPC instrument.
Under the support of the DOE SBIR Phase I program, we have developed and constructed two instrument prototypes for aerosol absorption measurements: one operates at 360nm and the other at 1064nm. The development of both devices is based on our patented differential photoacoustic technique. From the laboratory testing and evaluation, we obtained the following technical specifications for the two prototypes:
1) Photoacoustic measurements of aerosol light absorption at 360nm and 1064 nm
2) Detection limit of 1.0 Mm-1 in 10s-averaging and 0.36 Mm-1 in 100s at 1064nm
3) Detection limit of 9 Mm-1 in 10s at 360nm
4) Time response of 4.3 ± 0.6 s, using the 90% criteria
5) Linear dynamic range from 0.36 Mm to 250 Mm-1 at 1064nm
6) Sample flow rate of 0.5-2.0 liter per minute
7) Continuous measurement at 1s sampling rate
8) An aerosol-based calibration approach
9) Dimensions of 56cmx43cmx25cm and 25kg for the near-IR prototype; while 66cmx43cmx38cm and 30kg for the UV prototype.
In the SBIR Phase I study, we adopted a different modulation approach to the UV prototype from the near-IR instrument, to improve its detection sensitivity. However the different modulation schemes presents an obstacle to combining the UV and near-IR aerosol absorption monitors into a single two-wavelength measurement instrument.
