CHEMICAL VARIATIONS IN AMBER EXAMINED WITH TWO-PHOTON EXCITATION FLUORESCENCE MICRO-SPECTROSCOPY

Amber is plant resin which became fossilized and polymerized over a period of at least 100,000 years, a process through which shorter organic chains join to form much longer chains and massive networks. Amber is a valuable source of paleontological data because it stores important information about the trees which exuded the resin and also can preserve other fauna and flora as bioinclusions. In particular, resin is a physical and chemical defense against insect herbivores, and so the chemistry of the amber can preserve information relating to plant and insect interactions. We studied the chemistry of a number of samples of Spanish, Lebanese, and French amber from the Cretaceous, Baltic amber from the Eocene, and Dominican amber from the Miocene using two-photon excitation fluorescence micro-spectroscopy, which captures entire spectra of emitted light from samples excited with ultra-fast pulses of light. There have been some studies which have characterized amber chemistry using other methods, and there have been other studies detailing the fluorescence spectroscopy of amber specimens of a single type, but this is one of the first to use fluorescence spectroscopy as a method for distinguishing different specimens from different localities. Our study demonstrates a distinct difference in emission spectra between French and other types of Cretaceous amber, such as Spanish and Lebanese, as well as between Baltic and Dominican amber.