Laser induced break down(LIBS) is a method of analysis of materials. It is a kind of emission spectroscopy, very easy to analyse many kinds of elements at the same time. Since it was introduced for analytical field in 1962, especially in these two decades, LIBS has developed very fast. Now it has been researched not only in LABS, but in many field as well, such as metallurgy, cultural heritage and archaeology. Spectrograph also plays important role in LIBS system, despite of laser and fast detectors.
The LIBS contains Pulsed laser, focusing apparatus, sample holder, signal collecting apparatus, time control device (controlling the delay between laser and detector), spectrograph and fast response detector(often ICCD).
Fig1:Diagram of LIBS system
Nanosecond laser is often be used in LIBS. 532nm and 1064nm are two kinds of wavelength in the system. In recently years, femtosecond laser is also applied in LIBS, because of its ultrafast advantages.
ICCD is a kind of fast response detector, and a good choice for LIBS. But we can also try some other method to get LIBS signal. When the laser excites the sample, LIBS signal won’t appear immediately (microsecond after excitation). And it also lasts for microseconds. So, we can capture LIBS signal with the help of Time control device, which control the delay between laser and fast detector, such as Linear CCD not ICCD.
In recent years, Quantitative LIBS is a major part of LIBS research. It needs high stability of laser power, high time resolution of fast detector and time control device. Of course, spectrograph is also a key part. Echelle spectrograph is widely used in LIBS system, which can display the signal in a wide wavelength range. But higher resolution, smaller wavelength range in one shot, and more expensive. So, C-T(Czerny-Turner) spectrograph, a kind of conventional spectrograph is still popular, because of its advantages, such as price and easy to operation.
It’s very easy for C-T spectrograph to get higher resolution or wide one-shot range just by replacing different kinds of gratings. Compared with Echelle spectrograph, it’s also easy to achieve image corrected signal, which is important for high resolution and good peak profiles. So, that makes quantitative analysis much easier!
Zolix is concentrated on spectrograph for 20 years. We provide Omni series spectrographs, which is based on C-T configuration. Depends on focal length, we have 200mm, 320mm, 500mm and 750mm spectrographs. For example, for 750mm spectrograph, with 1200L/mm grating, the resolution will be 0.03nm, which is enough for LIBS signals.
Fig2: LIBS analysis of Codonopsis pilosula samples
The data shown above is the LIBS signal of Codonopsis pilosula sample. In this experiment, scientist used Omni-500 spectrograph and ICCD. We may find the resolution of spectrograph is high enough to distinguish the signals, which are very close to each other.
Omni series spectrograph is very versatile, we provide fiber adaptor, on the entrance port, also we can attach some kinds of signal point detector on the exit port.
Fig 3: we provide many kinds of combination of spectrograph
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