Raman 785nm / 1064nm:
Which Is Right for You?
Choosing the right excitation wavelength for your Raman application
Choosing the right excitation wavelength is one of the most important decisions when investing in a Raman spectroscopy system. Two of the most widely used laser wavelengths are 785 nm (near-infrared, partially visible) and 1064 nm (near-infrared). Each offers distinct advantages depending on your application and the nature of your samples.
Below, we explore the key differences, benefits, and ideal use cases for both technologies.
785 nm Raman Spectroscopy:
The Versatile Workhorse
The 785 nm wavelength is one of the most commonly used in Raman instruments because it offers an excellent balance between signal strength and fluorescence suppression.
Advantages:
- Stronger Raman signal compared to longer wavelengths
- Moderate reduction of fluorescence, better than 532/633 nm lasers
- Compatible with compact handheld systems
- Uses highly sensitive, high-pixel-count silicon CCD/CMOS detectors
- Ideal for routine analysis, organic compounds, biological materials, and pharmaceuticals
- Suitable for identification of many hazardous materials and even selected types of explosives
Limitations:
- Still susceptible to fluorescence in highly fluorescent or dark-colored samples
- May not produce usable spectra for some pigments, polymers, or natural substances
1064 nm Raman:
The Slower Fluorescence Fighter
When fluorescence becomes a serious problem, 1064 nm excitation can provide usable Raman spectra where shorter-wavelength systems fail. Although the Raman signal is inherently weaker, the better suppression of fluorescence can make 1064 nm the preferred choice for difficult samples.
Advantages:
- Reduced fluorescence, even from highly problematic samples
- Well suited for many highly fluorescent, pigmented, or aged materials (e.g. inks, pigments, soils)
- Allows analysis of artworks, historical artifacts, forensics, and natural substances
- Lower level of laser-induced heating and sample damage
Limitations:
- Weaker Raman signal, requiring longer integration times and special detectors (typically InGaAs) working far from visible spectral range
- Less suitable for weak signals, low-concentration samples / solutions, or trace-level detection
- Systems may be larger, more power-consuming, and more expensive due to the more demanding NIR detection technology.
- Typically coarser spectral sampling in compact dispersive systems
Side-by-Side Comparison
| Feature | 785 nm | 1064 nm |
|---|---|---|
| Raman Signal Strength | Higher | Moderate to Lower |
| Fluorescence Suppression | Medium | Higher |
| Detector Type | Silicon CMOS / CCD | InGaAs (usually cooled) |
| Measurement Speed | Faster | Typically slower |
| System Size & Cost | Compact, cost-effective | Larger, higher cost |
| Best For | Routine lab work, organics, pharma | Fluorescent samples, dark materials |
| Not Ideal For | Strongly fluorescent samples | Trace detection, fast screening |
Physical Principles Behind
the Different Properties
The different characteristics of 785 nm and 1064 nm Raman systems originate mainly from three fundamental physical effects.
Wavelength Dependence of Raman Scattering
The intensity of Raman scattering strongly depends on the excitation wavelength and approximately follows:
Raman intensity ~ 1/λ4
Consequently, increasing the excitation wavelength significantly reduces Raman scattering intensity, which approximately decreases as the inverse fourth power of the wavelength (λ). This fundamental relationship explains much of the difference in Raman signal intensity between 785 nm and 1064 nm excitation.
Photon Energy and Fluorescence
The energy of a photon is inversely proportional to its wavelength: E = hc/λ
Photons at 1064 nm therefore have lower energy than photons at 785 nm. As a result, they are less likely to excite electronic transitions responsible for fluorescence in many materials. This is the physical origin of the different fluorescence behavior observed with the two discussed wavelengths.
Detector Technology
Raman scattering shifts photons to wavelengths different from that of the excitation laser. With 785 nm excitation, Raman-scattered light can be efficiently detected using sensitive silicon-based CCD or CMOS detectors.
With 1064 nm excitation, the resulting Raman spectrum extends further into the near-infrared region, where silicon-based detectors rapidly lose sensitivity, so dispersive systems typically require InGaAs detectors. These are generally more expensive and often require cooling, contributing to higher system cost, power consumption, and overall complexity.
Sample Heating
Sample heating is determined mainly by the absorption of laser radiation by the material, together with laser power, spot size, and exposure time. A longer wavelength does not automatically mean less heating. Depending on the material, either wavelength may produce stronger absorption and therefore greater thermal effects.
Spectral Sampling
785 nm systems typically provide finer spectral sampling, largely due to the availability of high-resolution silicon CCD/CMOS line sensors. In typical compact implementations, InGaAs line sensors may have up to approximately four times fewer pixels than their silicon counterparts, resulting in coarser sampling of the Raman spectrum for a comparable optical configuration.
Choose 785 nm if you need:
- High sensitivity, measurement of low concentrations and near-trace-level detection
- Faster measurements
- A cost-effective solution
- A versatile, general-purpose Raman system
- fiber-optic and remote-probe measurements
Choose 1064 nm if you need:
- Cleaner spectra from highly fluorescent or visually dark, strongly absorbing samples
- Non-destructive analysis of sensitive materials
- High chemical specificity with minimal interference
Need help selecting
the right Raman system?
Both 785 nm and 1064 nm Raman spectroscopy offer powerful capabilities, but they serve different purposes.
If your work involves highly fluorescent materials, especially pigments, and the samples provide a sufficiently strong Raman response, 1064 nm may be the better choice. In practice, the choice of excitation wavelength is therefore a compromise between the wavelength dependence of Raman scattering, the probability of fluorescence excitation, and the spectral sensitivity of available detectors.
For most other applications, 785 nm offers an excellent balance of sensitivity, speed, cost, and versatility.
Contact our specialists for expert advice tailored to your samples and applications.