Spectroscopy Knowledge Center
Spectroscopy is one of the most powerful analytical techniques available for identifying materials,
measuring concentrations, monitoring processes, and characterizing physical and chemical properties.
By analyzing how light interacts with matter, spectroscopy provides fast, non-destructive, and highly
sensitive measurements for research, industrial, and OEM applications.
What is Spectroscopy?
Spectroscopy is the study of the interaction between light and matter. Different materials absorb,
transmit, reflect, emit, or scatter light in unique ways. These optical signatures act as fingerprints,
allowing scientists and engineers to identify substances, determine concentrations, and monitor
changes in real time.
Modern spectrometers measure light intensity as a function of wavelength, enabling highly accurate
material characterization in laboratory, field, and industrial environments.
Absorption Spectroscopy
Principle
Absorption spectroscopy measures the amount of light absorbed by a sample at specific wavelengths.
Molecules and atoms absorb photons only at energies corresponding to transitions between quantized
energy states. The resulting absorption spectrum provides a unique signature of the material.
How It Works
- A broadband light source illuminates the sample.
- The sample absorbs specific wavelengths.
- The transmitted light is collected by a spectrometer.
- The measured spectrum is compared to a reference spectrum.
- Absorbance is calculated to determine composition and concentration.
Beer-Lambert Law
The relationship between absorbance and concentration is described by:
A = εcl
- A = Absorbance
- ε = Molar absorptivity
- c = Concentration
- l = Optical path length
Typical Applications
- Chemical analysis
- Environmental monitoring
- Water quality testing
- Pharmaceutical analysis
- Process control
- Clinical diagnostics
- Material characterization
Transmission Spectroscopy
Principle
Transmission spectroscopy measures the amount of light that passes through a sample.
By comparing transmitted intensity to incident intensity, information about absorption
characteristics and sample composition can be obtained.
Advantages
- Simple optical setup
- Quantitative concentration analysis
- High sensitivity
- Suitable for gases, liquids, and transparent solids
Typical Applications
- UV-Vis spectroscopy
- NIR spectroscopy
- Gas sensing
- Chemical process monitoring
- Thin-film characterization
Reflectance Spectroscopy
Principle
Reflectance spectroscopy evaluates how much light is reflected from a surface as a function of
wavelength. The resulting spectrum provides information about surface composition, material
properties, color, texture, and coating characteristics.
Measurement Types
Specular Reflectance
Measures mirror-like reflections from smooth surfaces.
Diffuse Reflectance
Measures scattered light from rough surfaces, powders, biological samples, and other
non-specular materials.
Typical Applications
- Color measurement
- Coating inspection
- Semiconductor analysis
- Agricultural monitoring
- Mineral identification
- Food quality control
Benefits
- Non-contact measurement
- Suitable for opaque materials
- Fast inline inspection capability
Fluorescence Spectroscopy
Principle
Fluorescence spectroscopy measures light emitted by a material after excitation by an external
light source. Molecules absorb energy, move to an excited state, and subsequently emit light at a
longer wavelength as they return to a lower energy state.
Advantages
- Exceptional sensitivity
- High selectivity
- Fast response times
- Suitable for trace analysis
Typical Applications
- Life sciences
- Biomedical diagnostics
- DNA analysis
- Pharmaceutical research
- Environmental sensing
- Food safety testing
Raman Spectroscopy
Principle
Raman spectroscopy is based on the inelastic scattering of laser light by molecules.
A small fraction of the scattered light changes wavelength due to molecular vibrational
interactions. These Raman shifts provide highly specific molecular fingerprints that allow
direct chemical identification.
Advantages
- Minimal sample preparation
- Non-destructive analysis
- Direct molecular identification
- Suitable for solids, liquids, and gases
- Can often measure through glass containers
Typical Applications
- Pharmaceutical research
- Material science
- Polymer identification
- Semiconductor characterization
- Forensic investigations
- Battery research
Information Obtained
- Molecular structure
- Chemical composition
- Crystallinity
- Phase identification
Laser-Induced Breakdown Spectroscopy (LIBS)
Principle
Laser-Induced Breakdown Spectroscopy (LIBS) uses a high-energy laser pulse to generate
a micro-plasma on the sample surface. The plasma emits characteristic wavelengths that
reveal the elemental composition of the material.
Benefits
- Little or no sample preparation
- Real-time analysis
- Multi-element detection
- Suitable for solids, liquids, and gases
- Remote measurement capability
Typical Applications
- Metallurgy
- Mining and geology
- Metal recycling and sorting
- Industrial quality control
- Environmental monitoring
- Defense and security
Information Obtained
- Elemental composition
- Alloy identification
- Contamination detection
- Process monitoring
Components of a Spectroscopy System
Light Sources
- Tungsten-halogen lamps
- Deuterium lamps
- Xenon arc lamps
- LED light sources
- Laser sources
Sampling Optics
- Fiber optic probes
- Reflection probes
- Transmission cells
- Integrating spheres
- Microscope optics
Spectrometer
The spectrometer disperses incoming light into individual wavelengths and measures the
intensity distribution across the spectrum. Modern systems often utilize diffraction gratings
and array detectors for rapid spectrum acquisition.
Software
- Spectrum visualization
- Quantitative analysis
- Chemometric modeling
- Real-time process monitoring
- Automated reporting
Why Choose Spectroscopy?
- Non-destructive measurements
- Fast analysis
- High sensitivity
- Real-time monitoring
- Minimal sample preparation
- Remote sensing capabilities
- Scalable from laboratory to industrial environments
Spectroscopy Solutions from Te Lintelo Systems
Te Lintelo Systems (TLS) supplies advanced spectroscopy solutions for research laboratories,
OEM developers, and industrial users throughout the Benelux.
- UV-VIS spectrometers
- NIR spectrometers
- Miniature spectrometers
- High-resolution spectrometers
- Fiber optic accessories
- Light sources
- Reflection and transmission probes
- OEM spectroscopy modules
- Integrated sensing solutions
Whether your application requires absorption, reflectance, fluorescence, Raman, or LIBS
measurements, the spectroscopy specialists at Te Lintelo Systems can help you select and
integrate the optimum solution.
Spectroscopy Terms
Resolution
The resolution of a spectrometer describes its ability to distinguish between two closely spaced wavelengths. It is typically expressed as the Full Width at Half Maximum (FWHM), which represents the wavelength difference at half the height of a spectral peak. Factors such as grating, slit width, wavelength range, and detector pixel count influence resolution. A smaller FWHM indicates better performance.
Stray Light
Stray light refers to unwanted light that reaches the detector due to internal scattering, reflection, or refraction. It is commonly evaluated by measuring residual light at a blocked wavelength, for example using a high‑pass filter. Lower stray‑light levels improve measurement accuracy.
Dark Noise
Dark noise is the electronic noise generated by the detector and readout electronics when no light is present. It is usually measured as the RMS voltage output during a short integration period in complete darkness. Lower dark noise enhances sensitivity, particularly for low‑light measurements.
Signal-to-Noise Ratio (SNR)
The signal‑to‑noise ratio compares the detector’s maximum measurable signal to the noise present in the system. A higher SNR results in a cleaner, more stable output and improves the detection of small intensity variations. It is often calculated using the full‑scale detector signal divided by the RMS noise.
Integration Time
Integration time is the duration over which the spectrometer collects light to generate a single spectrum. Longer integration times increase signal intensity and improve SNR, while very short times are limited by the characteristics of the CCD or CMOS sensor. Typical user‑defined ranges span from milliseconds to more than one minute.
Dynamic Range
Dynamic range expresses the ratio between the smallest and largest signals a spectrometer can measure accurately. A larger dynamic range allows the simultaneous detection of both weak and strong signals without saturation or loss of detail.
Thermal Stability
Thermal stability refers to how consistently a spectrometer performs across varying temperatures. Evaluations are typically made within a defined temperature range to ensure stability in wavelength and intensity under different environmental conditions.