THE STORY
On an otherwise uneventful Monday morning, Bill the Baker and Moe the Milkman set about making their usual delivery rounds. Little do they know of the terrible misfortune in store for them both. As Moe cautiously approaches the corner of Broadway and 113th St., he is shocked to see Bill's Bread Truck suddenly burst into flames. Moe, realizing that the only way to save his pal Bill is to steer his liquid cargo directly into the ensuing flames, hesitantly but courageously does so. Luckily both men escape with minor injuries, but their precious cargos have been mixed up. Less than a second later, a wild horde of ambulance chasers arrive and begin photographing the accident scene with their new ultra-high resolution cameras. After consulting with his lawyer, Bill decides to sue Moe for damages, claiming that his truck was never on fire. Good thing they took those photos! The cameras are so powerful that from the photos investigators can not only count how many bread loaves and milk bottles are on each truck, but they can even distinguish loaves of pumpernickel from loaves of rye and bottles of skim milk from bottles of whole milk. Moe's lawyers make use of the amazingly accurate evidence to reconstruct the conditions of the crash, including the speeds and trajectories of the two vehicles, and thereby prove Moe's innocence.
THE EXPLANATION
In our research, the trucks we collide are vibrationally excited molecules (typically large aromatic hydrocarbons like pyrasine, methyl pyrasine, pyradine, pyrimadine, & C6F6) with room temperature bath molecules (typically CO2 & CO). Our cameras are high-resolution infrared diode lasers and the bread loaves and milk bottles we observe are the post-collision vibrational, rotational and translational degrees of freedom of the bath molecules on a single-collision time scale. From these snapshots, we gain information about the the collision itself.
For example, we can determine the average energy transfer/collision and the probability of this transfer and then construct a probability distribution, P(E, E'), for the energy transfer. This in turn allows us to calculate the unimolecular decomposition rate constant, which describes how long it would take for the vibrationally molecules to decompose had the bath molecules not "extinguished" the excited state. Sort of like the police using the crash photos to determine how long Bill had to live before his truck would explode had it not been for Moe's quick thinking.