【讨论】辉光?

2.    Principles of the GDOES techniques
This application note focuses on the performance of the Spectruma GDA 750 HP for the bulk analysis of cast irons. We will, however, demonstrate the interest of keeping the depth profile capability even for bulk analyses of cast iron. We will further compare the performance of the GDOES technique to the traditional Spectro Cast instruments.
2.1.    Glow discharge light source.
A hollow anode glow discharge chamber serves as the light source for the spectrometer. The two electrodes of the discharge cavity are designed as a tubular grounded copper tube and the flat sample to be analysed. In fact, the sample closes the discharge cavity: Sample introduction is therefore extremely simple. The electrical power is supplied directly to sample. A regulated negative voltage 900 Volts DC is supplied. The carrier gas within the discharge cavity is high purity Argon (5.6 or higher). The Argon pressure in the cavity is maintained at about 4 Pascal. The Argon flow and as a consequence the Argon pressure is regulated to maintain a discharge current of 40 mA. Under these condition a flow of about 0.2l/min sweeps the cavity to ensure a clean Argon atmosphere during the analyses process.
The analytical figures of merit of the GDOES technique are closely linked to the physics of the glow discharge.
A plasma is created within the tubular grounded anode. The electrical power to ignite and maintain the plasma is fed through the sample, which acts as the cathode. Argon ions and free electrons are generated in the plasma (1). The potential difference between the plasma and the sample accelerate the Argon ions towards the sample(2). The ions bombard the sample surface with an average kinetic energy of 100 eV (3). This bombardment creates a sputtering process, atoms from the sample surface leave the sample lattice. In addition to the atoms some free electrons, called secondary electrons, are generated during the sputtering process as well (4). The secondary electrons are accelerated towards the plasma and maintain the plasma activity. The atoms diffuse towards the plasma. Here they may be excited (7) or ionised through collisions with free electrons, Argon ions or meta-stable Argon atoms (5). The excited analyte atoms subsequently relax to the energetic ground state by emission of characteristic photons (6). The characteristic photon spectrum is observed through the observation window.
In fact, the analyte atoms, after being sputtered from the surface, are diluted in the Argon atmosphere of the plasma and excited as single atoms. It is this separation of sputtering and excitation as well as the dilution in the Argon plasma, that makes GDOES analyses widely independent of matrix effects. The low density of analyte atoms leads also to a reduction of self-absorption and allows therefore the observation of mainly straight calibration lines.
The discharge chamber is designed to achieve flat sputter craters. The average energy of Argon ions bombarding the sample surface is only 100 eV. At this low energy the Argon ions do not penetrate deeply into the sample latice. Only atoms from the outmost atomic layers are removed from the sample surface. The combination of flat crater bottoms and moderate ion energy assures a good depth resolution of the GDA 750. It allows to characterise the chemical composition of the sample layer by layer, from the surface into the core material.

我所知道，主要用在碳钢冷轧板，镀锌板指纹板工业检测上，属于发射光谱

我是光电直读光谱仪的，顶一个！！

应助达人

呵呵,小康你是用的SPECTRO的GDA750吗,现在目前也就3家.LECO JY SPECTRO 3家吧.质谱好象不太清楚,但是我看现在的发表的文章好象不怎么多,其实我感觉它能做的东西还是很多的.但是目前为什么好象有点不被认可吗?

你好！
我很久没有上来了，如果有问题，给我电话好了。我去你实验室的时候，给你留过我的电话的。
分析中碰到的问题，多多交流吧。

应助达人

多谢张工,你一直很忙,我这边的仪器现在工作的应用好象大家不怎么感冒,我也不知道它现在做什么比较好,我以后有问题还会向你多请教.在这里先谢谢了.

我是搞GDS的，我们铝合金的锌老测不准，交流下呀

我们的仪器刚装好，还没有怎么用呢