Abstract In this work, we investigate the impact of data provided by complementary laser-based spectroscopic methods on multivariate classification accuracy. Discrimination and classification of five Staphylococcus bacterial strains and one strain of Escherichia coli is presented. Obtained spectroscopic data were then processed using Multivariate Data Analysis algorithms.
YAG Spectroscopy breakdown laser and a spectrometer with a wide spectral range and a high sensitivity, fast response rate, time gated detector.
This is coupled to a computer which can rapidly process and interpret the acquired data. As such LIBS is one of the most experimentally simple spectroscopic analytical techniques, making it one of the cheapest to purchase and to operate.
YAG laser generates energy in the near infrared region of the electromagnetic spectrumwith a wavelength of nm. Other lasers have been used for LIBS, mainly the Excimer Excited dimer type that generates energy in the visible and ultraviolet regions.
The spectrometer consists of either a monochromator scanning or a polychromator non-scanning and a photomultiplier or CCD detector respectively. The most common monochromator is the Czerny—Turner type whilst the most common polychromator is the Echelle type.
However, even the Czerny-Turner type can be and is often used to disperse the radiation onto a CCD effectively making it a polychromator. The polychromator spectrometer is the type most commonly used in LIBS as it allows simultaneous acquisition of the entire wavelength range of interest.
The spectrometer collects electromagnetic radiation over the Spectroscopy breakdown wavelength range possible, maximising the number of emission lines detected for each particular element.
All elements have emission lines within this wavelength range. The energy resolution of the spectrometer can also affect the quality of the LIBS measurement, since high resolution systems can separate spectral emission lines in close juxtapositionreducing interference and increasing selectivity.
This feature is particularly important in specimens which have a complex matrixcontaining a large number of different elements. Accompanying the spectrometer and detector is a delay generator which accurately gates the detector's response time, allowing temporal resolution of the spectrum.
Advantages[ edit ] Because such a small amount of material is consumed during the LIBS process the technique is considered essentially non-destructive or minimally-destructive, and with an average power density of less than one watt radiated onto the specimen there is almost no specimen heating surrounding the ablation site.
Due to the nature of this technique sample preparation is typically minimised to homogenisation or is often unnecessary where heterogeneity is to be investigated or where a specimen is known to be sufficiently homogeneousthis reduces the possibility of contamination during chemical preparation steps.
One of the major advantages of the LIBS technique is its ability to depth profile a specimen by repeatedly discharging the laser in the same position, effectively going deeper into the specimen with each shot. This can also be applied to the removal of surface contamination, where the laser is discharged a number of times prior to the analysing shot.
LIBS is also a very rapid technique giving results within seconds, making it particularly useful for high volume analyses or on-line industrial monitoring. LIBS is an entirely optical technique, therefore it requires only optical access to the specimen.
This is of major significance as fiber optics can be employed for remote analyses. And being an optical technique it is non-invasive, non-contact and can even be used as a stand-off analytical technique when coupled to appropriate telescopic apparatus.
These attributes have significance for use in areas from hazardous environments to space exploration. Additionally LIBS systems can easily be coupled to an optical microscope for micro-sampling adding a new dimension of analytical flexibility.
With specialised optics or a mechanically positioned specimen stage the laser can be scanned over the surface of the specimen allowing spatially resolved chemical analysis and the creation of 'elemental maps'.Laser-induced breakdown spectroscopy (LIBS) is a minimally destructive type of atomic emission spectroscopy that does not need any sample preparation [unlike alternative techniques such as scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDX)] and will provide information on the local distribution of elements at relatively.
In honor of Spectroscopy's celebration of 30 years covering the latest developments in materials analysis, we asked a panel of experts to assess the current state of the art of laser-induced breakdown spectroscopy (LIBS), and to try to predict how technology will develop in the future.
Combination of laser-induced breakdown spectroscopy and Raman spectroscopy for multivariate classification of bacteria ☆. Laser induced breakdown spectroscopy (LIBS) is basically an emission spectroscopy technique where atoms and ions are primarily formed in their excited states as a result of interaction between a tightly focused laser beam and the material sample.
Laser-induced breakdown spectroscopy (LIBS) is an atomic emission spectroscopy. Atoms are excited from the lower energy level to . Laser-induced breakdown spectroscopy (LIBS) is a type of atomic emission spectroscopy which uses a highly energetic laser pulse as the excitation source.
The laser is focused to form a plasma, which atomizes and excites samples.