Spectroscopy 101: Types of Spectra and Spectroscopy

Introduction to Spectroscopy

Spectroscopy is the study of how different materials emit and interact with light at different wavelengths.
It helps determine the temperature and composition of objects without direct sampling.

Light is separated into component colors using prisms or diffraction gratings to form a spectrum.
Spectroscopes and spectrographs are tools used to capture and measure spectra.
Spectra can be represented as images or graphs showing brightness vs. wavelength.
Graphs reveal subtle color differences not visible to the naked eye.
Example: Spectrum of star Altair, showing emission and absorption lines.

Continuous Spectrum: Contains all wavelengths; emitted by hot, dense objects.
- Blackbody curve is a type of continuous spectrum.
- Useful for calculating temperature based on peak wavelength.
Emission Spectrum: Shows colored lines emitted by a glowing gas.
- Corresponds to specific atoms and their light emission patterns.
- Useful for studying hot gas clouds and their composition.
Absorption Spectrum: Continuous spectrum with missing colors, shown as black lines.
- Occurs when light passes through gas, with atoms absorbing specific wavelengths.
- Helps identify elements in gas by their unique absorption lines.

Continuous, emission, and absorption spectra can be visualized together.
Light interaction with gas can lead to absorption or heating, causing emission.
Spectra types are interconnected; absorption and emission lines have inverse relationships.

Reflectance spectra show colors reflecting off a surface.
Used to study Earth and planetary surfaces, determining material composition.
Reflectance spectra are complex, influenced by many factors like surface texture.

Human color vision uses basic spectroscopy principles to distinguish materials.
Differences in color perception in daily life are a result of light absorption and reflection.

Spectroscopy provides detailed insights into the universe by analyzing how light interacts with matter.
Different spectra types offer unique information about temperature, composition, and material characteristics.