The Flowing Afterglow

Aside from my main project, I have been helping get another mass spectrometer in the lab up and running: the flowing afterglow.  This instrument allows us to conduct reactions in the flow tube to produce ions using volatile compounds.  In addition, temperature and pressure can be controlled in the instrument to create an atmospheric environment for these reactions.

Work began on the flowing afterglow in our lab a the beginning of the summer when we the Roots pump (that had been sent out in October for repairs) was returned.  We reinstalled the pump, made some changes with the plumbing, updated software for producing the mass spectrum, and changed oil.  We used a variety of source gasses to calibrate the scale of the computer mode for the instrument, including methane, fluorine gas, nitrous oxide, and more.  A way to introduce sample into the flow tube when it is a liquid, is the “freeze, thaw, vent” method.  This method freezes the chemical (ie. chloroform) using liquid nitrogen, and allows the vapors to enter the flow tube as it thaws.  Currently, we  are creating a program to reformat data so that it can be inputted into a Crunch software for interpretation of scans and production of relevant energy graphs.

A flowing afterglow mass spectrometer can work in a variety of modes.  The modes that we mostly have been toying with since we have gotten it working.  Q1 mode is where the first quadrapole acts as the mass analyzer while Q2 and Q3 are pipes which “focus”the selected ions.  Q3 mode is of a similar nature except the ions are focused through the first and second quadrapoles, and the third quadrapole is the mass analyzer.  To focus on particular peaks/masses, we use product ion mode to fix the Q1 analyzer, focus ions through Q2, and use Q3 as a scanning mass analyzer.

Reactions via the source gas valves in the flow tube (left) create ions that enter into the mass analyzer, which in this case is a triple quadrapole (right).

Reactions via the source gas valves in the flow tube (left) create ions that enter into the mass analyzer, which in this case is a triple quadrapole (right).

We hope that in the future, we can use this instrument to conduct experiments for the determination of the energy required to break bonds to create ions.