探测低温固体基质中的单个Yb原子

The aim of the present project is to detect a single Ytterbium (Yb) atom isolated in a cryogenic matrix. This will be an important proof principal because almost all species can be stabilized in a cryogenic matrix, including transient and reactive species difficult to maintain in the gas-phase. The techniques employed will be those of conventional Matrix Isolation Spectroscopy (MIS): the Yb atom is implanted in a transparent CH4 crystal and then characterized through fluorescence spectroscopy. In practice, the matrix is grown by directing a flux of gas onto a CaF2 window thermally anchored to the cold head of a closed-cycle helium dewar. A flux of Yb atoms generated from an effusion oven is then directed at the matrix during its growth. Once the matrix has been prepared, the decay products from optical pumping of the strong Yb singlet transition will be characterized using a PMT. The researcher intends to develop the theoretical and experimental methods for detecting a single Yb atom under matrix conditions. It is expected that this can be achieved by depositing ultra-low Yb concentrations and using high efficiency optics to collect the fluorescence.

本研究项目的重点是探测低温固体基质中的单个Yb原子，它可以作为能否实现低温惰性基质中的单原子捕获的“proof of principle”依据。该研究将采用传统的基质隔离光谱(MIS)技术: Yb原子被植入（隔离于）一个固态CH4气体晶体（基质）中，然后探测其荧光光谱。在实际应用中，通过直接将CH4气体喷于液氦低温冷头制冷的CaF2窗片上实现基质生长。Yb的热原子束在炉子中产生，并在基质生长过程中持续喷入。基质制备好后，激发Yb的单重态强跃迁，利用光电倍增管观察荧光光谱弛豫过程。研究者的目标是发展理论和实验技术，实现在隔离环境下Yb样品的单原子分辨率测量。预期可以通过超低浓度的Yb原子沉积和超高的荧光收集效率实现这一目标。

The aim of the project was to detect a single Ytterbium (Yb) atom in a cryogenic matrix. The techniques employed were those of conventional Matrix Isolation Spectroscopy (MIS): the Yb atoms is implanted in a transparent crystal and then characterized through fluorescence spectroscopy. In practice, the matrix is grown by directing a flux of gas onto as CaF2 window thermally anchored to the coldhead of a closed-cycle helium dewar. A flux of Yb atoms generated from an effusion oven is then directed at the matrix during its growth. Once the matrix was been prepared, the decay products from optical pumping of the strong Yb singlet transition will be characterized using a photon counter. Originally CH4 was chosen to be the matrix gas, but experiments showed that the rare gases have better characteristics for single atom detection.