Black Bag Experiments at PSI

Today is my first work-related posting. The whole reason I'm even here is for taking part in some chamber studies at PSI (the Paul Scherrer Institut) located north of Zurich, more precisely between and north of Baden and Brugg. I'm here sampling with the High Resolution Time-of-Flight Aerodyne Aerosol Mass Spectrometer, and if that's not a mouth full then I don't know what is. This is a picture of Megan and Rami just under the black bag from which we did a dark experiment (no lights = no photoinduced reactions) today. Most people were at ToFWerk today, the makers of our power supply so it was a relatively quiet and uncrowded day, proving to be very nice indeed.

Sadly, our efforts were not rewarded in that our sampling did not replicate the experiment we attempted to repeat. Just as a brief note: we were attempting to replicate a published experiment with increased instrumentation in order to gain increased insight to the chemical mechanisms of the reaction. Four compounds were to be atomized into the black bag and sampled over a period of 2 hours, whereupon polymers were to form. However, our sample solution was so concentrated and of a higher pH that it seems we did not have the same solution. Of course this was realized after the completion of one experiment with no change of the particles in the bag over 2 hours.

One hypothesis was that we had a polymer solution before we even started. VTDMA (Volatility Tandem Differential Mobility Analyzer, which to make it simple determines the percentage of the particles remaining after heating, a.k.a. the non-volatile fraction) readings were of much higher percentages than expected. Upon further investigation this was proved to be true for the original solution and later low concentration versions. Therefore, further replications of the experiment were aborted. However, this was all determined at about 7:30 pm.

Although our efforts were unfruitful, I think the crew left behind enjoyed all efforts throughout the day. For me, it was the first time I was the sole operator of the HR-ToF AMS during a field campaign, and not only was it empowering, exciting and exhilarating, it definitely gave me confidence in my ability to run the instrument and with high precision. Unfortunately, I didn't get a chance to show my talents and sample in all 3 modes (W, V, and negative ions), but that doesn't matter. I'm just glad to have finally been in this situation. I don't think it will help get me more credibility as an educated user, but it was great to finally be in on the action. Usually there are too many people around to be involved in everything and know why each decision is being made, along with the fine details of how the actual experiments are being executed. I think everyone deserves an individual chance such as this in order to actually understand what we're trying to do and participate in the decisions and data collection, especially if they are involved in any way with the future data analysis of the work.