西安无线电八厂生产的YYG-2型冷原子荧光测汞仪具有灵敏度高、选择性好和线性范围较广等优点,但也存在不稳的问题。根据我们使用的经验来看,气路是影响灵敏度和稳定性的关键部位,有如下几个因素影响,并提出相应的消除方法。一空气对汞原子荧光的淬灭基态汞原子吸收光辐射“活化”以后就处于不稳定的激发状态,它可能发射荧光释放能量,也可能与某些原子或分子碰撞发生能量传递,使之丧失能量,这时荧光将会减弱或者完全不产生,这种无辐射去激发过程称为荧光淬灭。Cavalli等指出:空气强烈地抑制荧光信号,因为淬灭激发了的汞原子,主要是氧气。很明显YYG-2型这种气路系统和荧光池都并非全密闭式的,因此激发区的空气浓度的高低直接影响荧光信号的强度(即灵敏度),而激发区周围介质的组成(载气和空气的混合)变化直接引起荧光强度的变化,严重地影响稳定性。为此我们设计了如图1所示的实验装置,在反应瓶的出口端接上一个玻璃三通阀,这样当 YYG-2 type cold atomic fluorescence mercury detector produced by Xi’an Radio Eight Factory has the advantages of high sensitivity, good selectivity and wide linear range, but also has the problem of instability. According to the experience we use, the gas path is a key part of the sensitivity and stability, with the following several factors, and put forward the corresponding elimination method. An atmosphere of mercury atom fluorescence quenching Ground state mercury atoms absorb light radiation “activation” after instability in the excitation state, it may emit fluorescence release energy, it may also collide with some atoms or molecules of energy transfer, so that Of the loss of energy, then the fluorescence will be reduced or not at all, this non-radiative deactivation process called fluorescence quenching. Cavalli et al. (1997) pointed out that air strongly suppresses the fluorescence signal because it quenches the excited mercury atoms, mainly oxygen. Obviously, YYG-2 type gas channel system and fluorescence cell are not totally enclosed. Therefore, the concentration of air in the excitation area directly affects the intensity (ie, sensitivity) of the fluorescence signal. The composition of the medium around the excitation area And air mixture) changes directly caused by fluorescence intensity changes, seriously affecting the stability. To this end, we designed the experimental setup as shown in Figure 1. A glass three-way valve was attached to the outlet of the reaction flask so that when