By varying the time interval between the two pulses it is possible to see how quickly the original molecule is transformed. The time interval between the pulses can be varied simply by causing the probe pulse to make a detour via mirrors. When the distance between the sodium nucleus and the iodine nucleus is short the covalent bond dominates, while the ion bond dominates at a greater distance. The vibrations may be compared to those of a marble rolling back and forth in a dish. OH a reaction that takes place in the atmosphere and in combustion.
Research is extra interesting when the results are unexpected.
When the two molecules become sufficiently close together they form a complex. The laser flash causes an electron to be shot from the benzene molecule into the iodine molecule. This then becomes negatively charged while the benzene molecule becomes positively charged. The negative and positive charges cause the benzene and the nearest iodine atom to be rapidly drawn to one another. The bond between the two iodine atoms is stretched when one of them is sucked in towards the benzene, whereupon the other atom breaks free and flies away.