Spectrometer vs Spectrophotometer

Spectrometers and spectrophotometers are two commonly used instruments in scientific research, particularly in the field of spectroscopy. The terms "spectrometer" and "spectrophotometer" are frequently used interchangeably, especially when discussing optical spectrometers. Which term you use depends on your scientific discipline, measurement technique, or even the preferences of your lab group.

Both instruments can split light into its constituent wavelengths and measure intensity at specific wavelengths. Typically, spectrophotometers are used in biological, life sciences and chemistry, where as spectrometer (oroptical spectrometer) is the term used in physical sciences.

One key difference is that spectrophotometers tend to be large, enclosed units used to measure specific properties of absorbance, tranmission or luminescence. However, spectrometer refers to the measurement device itself. For example, a spectrometer can be integrated with other optics components on an optical bench.

Spectrometer Definition vs Spectrophotometer Definition

"Spectrometer" is a general term for a piece of equipment that can separate and measure spectral components of a "physical phenomenon". Spectrometers can be designed to measure various phenomena such as electromagnetic light (for example, optical spectrometer and IR spectrometers), mass, or nuclear magnetic resonance. In this article, we will refer to optical spectrometers as spectrometers for comparison purposes.

Our research shows that there is not one firm definition for a spectrophotometer, and its usage or purpose varies. The word spectrophotometer comes refers to both a spectrum ("spectro") and light ("photo"). One definition states that a spectrophotometer is an instrument that measures the intensity of light that is absorbed by passing through a sample. One key distinction is that all spectrophotometers contain a spectrometer or incorporate a spectrometer within their design.

Applications and Usage

As stated, the term spectrometer can be used interchangeably with spectrophotometer. Some definitions describe a spectrophotometer as a spectrometer used for specific absorbance measurements specifically. Another says that spectrophotometry is the act of measuring a material with a spectrometer.

Spectrophotometers are often associated with life sciences, medicine, and biological applications. They are commonly used to measure absorbance or transmittance of light at specific wavelengths, particularly in biosensors, DNA analysis, and biological reaction studies. By measuring these properties, spectrophotometers can determine the concentration or optical density of a material or a biological sample.

Spectrometers, on the other hand, are frequently employed in chemical and physical sciences. They are used to measure the intensity of light at different wavelengths, providing valuable information about the distribution of wavelengths in a given sample or light source.

The term "spectrophotometer" is sometimes used to describe a handheld device specifically designed for color measurement. These spectrophotometers are used in a field of spectroscopy called colorimetry, which focuses on quantitatively measuring the color of light. Taking accurate color measurement is very important for various industries, such as in designing pigments and dyes, when characterising LEDs and within the food industry.

Spectrometer Components vs Spectrophotometer Components

One difference between spectrometers and spectrophotometers lies in their components. Spectrophotometers will always include a spectrometer. In some cases, spectrophotometers will have a built-in light source and all spectral components will be contained within one large, calibrated unit. This keeps components aligned, and there is a designated sample holder. Alternatively, a spectrophotometer may contain a spectrometer (to measure the intensity of light at different wavelengths) and a photometer (to measure luminous intensity). These instruments split light into its constituent components using a monochromator and employ a photoresistor or photodiode to measure the power of light incident on the spectrometer. These enclosed units allow for high levels of calibration within the system, but it can be difficult to identify and replace individual components if they break.

Spectrometers can be standalone components. These spectrometers can be fixed to an optics bench and must be used in conjunction with a separate light source and sample holder. These components can be manually aligned or connected with optical fibers, allowing more flexibility. Modular spectrometers can be adapted for many purposes such as absorbance spectroscopy or fluorescence spectroscopy and can be incorporated into most laboratories. However, these modular systems will require more regular alignment and may not be as precise. Some spectrometers also come in one integrated unit like spectrophotometers.

Key Differences Between Spectrometer and Spectrophotometer

Design and Modularity: Spectrophotometers are typically self-contained units with fixed components, including a light source and a spectrometer. In contrast, spectrometers are often modular and can be used in combination with a range of sample holders and light sources. Spectrometers are commonly part of modular setups where light sources are sold separately.

Sample Handling: Spectrophotometers are designed for specific purposes and sample types, often requiring designated sample holders. They are usually designed to measure liquid samples in standard cuvettes like the Ossila Quartz cuvette. Spectrometers, on the other hand, can accommodate different sample cells and configurations, allowing measurements under various conditions, including different temperatures.

Choosing the Right Instrument

When selecting between a spectrometer and a spectrophotometer, consider the specific requirements of your application. If you are taking one measurement consistently, e.g., you are measuring absorbance or transmittance of light at specific wavelengths in biological samples, a spectrophotometer may be more suitable for your needs. For broader measurements of light intensity across various wavelengths or applications in chemistry and physics, a spectrometer would be a better choice.

Understanding the distinctions between spectrometers and spectrophotometers will help you make an informed decision and ensure that your instrument meets your research needs.