Paolo De Natale of the Italian National Research Council (CNR) and the European Laboratory for Non-Linear Spectroscopy (LENS), both in Florence, Italy, and his colleagues, unveiled a new high-sensitivity technique last year called saturated-absorption cavity ring-down spectroscopy (SCAR): Saturated-Absorption Cavity Ring-Down Spectroscopy (ref. Physical Review Letters, 104, 110801, March 2010. G. Giusfredi, S. Bartalini, S. Borri, P. Cancio, I. Galli, D. Mazzotti, P. De Natale; Istituto Nazionale di Ottica INO-CNR , and European Laboratory for Nonlinear Spectroscopy ). A new article, published 30 December 2011, explain the improved methd: Molecular Gas Sensing Below Parts Per Trillion: Radiocarbon-Dioxide Optical Detection (Phys. Rev. Lett. 107, 270802. I. Galli, S. Bartalini, S. Borri, P. Cancio, D. Mazzotti, P. De Natale, G. Giusfredi). To determine the age of a sample, the SCAR technique uses a highly stable infrared laser to excite carbon dioxide molecules in a mirrored cavity.