Faculty of Physics, University of Vienna, VCQ & QuNaBioS, Boltzmanngasse 5, A-1090 Vienna, Austria.
Phys Rev Lett. 2014 Jun 27;112(25):250402. doi: 10.1103/PhysRevLett.112.250402. Epub 2014 Jun 25.
We measure the absolute absorption cross section of molecules using a matter-wave interferometer. A nanostructured density distribution is imprinted onto a dilute molecular beam through quantum interference. As the beam crosses the light field of a probe laser some molecules will absorb a single photon. These absorption events impart a momentum recoil which shifts the position of the molecule relative to the unperturbed beam. Averaging over the shifted and unshifted components within the beam leads to a reduction of the fringe visibility, enabling the absolute absorption cross section to be extracted with high accuracy. This technique is independent of the molecular density, it is minimally invasive and successfully eliminates many problems related to photon cycling, state mixing, photobleaching, photoinduced heating, fragmentation, and ionization. It can therefore be extended to a wide variety of neutral molecules, clusters, and nanoparticles.
我们使用物质波干涉仪测量分子的绝对吸收截面。通过量子干涉，将纳米结构的密度分布压印到稀释的分子束上。当光束穿过探测激光的光场时，一些分子将吸收一个单光子。这些吸收事件会给分子施加一个动量反冲，从而改变分子相对于未受扰束的位置。在光束中的偏移和未偏移分量上进行平均会导致条纹可见度降低，从而可以高精度地提取绝对吸收截面。该技术不依赖于分子密度，它的侵入性最小，并成功消除了与光子循环、态混合、光漂白、光致加热、碎裂和电离相关的许多问题。因此，它可以扩展到各种中性分子、团簇和纳米颗粒。
