Chemical Dynamics Laboratory

Laser setup

In the Chemical Dynamics Laboratory (CDL) at MIT, we have designed and built a novel apparatus to measure the temperature- and pressure-dependent chemical kinetics and the product-branching ratios of gas-phase radical reactions that are important in combustion. The reaction kinetics are determined using multipass laser absorption spectrometry (LAS), which provides high-quality overall reactions rates by measuring the time-dependent concentration of radicals quasi-continuously. The product-branching ratios are determined using time-resolved vacuum ultraviolet photoionization time-of-flight mass spectrometry (VUV PI TOF‑MS), which provides quantitative information on the relative amounts of the products formed during the course of reaction. Historically, LAS and VUV PI TOF-MS experiments are carried out in separate systems that are usually owned by separate research groups at different universities. So, even with close collaboration, it is often difficult to exactly replicate the experimental conditions to directly compare the results from an LAS experiment with those from a VUV PI TOF-MS experiment. Our design is the first in the world to combine both experiments in a single apparatus. By carrying out these two experiments simultaneouslyin the same apparatus, we effectively eliminate the systematic differences that exist when using two separate apparatuses andthus we candirectly compare the results from both methods.

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