Infrared Spectroscopy Lab

Transmission Spectral Analyzer

Simulate how starlight passes through the outer gaseous envelope of an alien world. Discover why distinct quantum molecular bonds create unique absorption fingerprints.

Interactive Astrophysics Lab

Transmission Spectrometer & Molecular Fingerprint Analyzer

Simulate JWST/NIRSpec transmission spectroscopy across exoplanetary atmospheres.

Target Molecule / Gas

Host Star Class

Detector Instrumental Noise10 ppm

Spectral Diagnostics

Water Vapor (H₂O)

Key indicator of liquid surface oceans or steam atmospheric envelopes in temperate terrestrial exoplanets and hot Jupiters.

Observational Note: Detected in WASP-96b, K2-18b, and Jupiter's icy moons.

Simulated Normalized Flux vs. Absorption Wavelength

SNR: ~100.0:1

940 nm (NIR) (Abs: 65%)

1.15 μm (J-Band) (Abs: 75%)

1.40 μm (H-Band) (Abs: 90%)

1.90 μm (K-Band) (Abs: 85%)

2.60 μm (MIR) (Abs: 95%)

1.000 Flux (Continuum)Transmission Dip Depth ΔF/F (%)

0.6 μm (Optical)1.5 μm (NIR)3.0 μm4.5 μm15.0 μm (Mid-IR)

940 nm (NIR)

940 nm

Dip: -65%

1.15 μm (J-Band)

1150 nm

Dip: -75%

1.40 μm (H-Band)

1400 nm

Dip: -90%

1.90 μm (K-Band)

1900 nm

Dip: -85%

2.60 μm (MIR)

2600 nm

Dip: -95%

How Transmission Spectroscopy Works

When an exoplanet passes in front of its host star (a transit), the planet blocks a portion of the starlight. While the opaque planetary disk blocks all wavelengths equally, the thin transparent atmosphere absorbs light only at specific wavelengths corresponding to the rovibrational quantum transitions of its atmospheric gases.

The Beer-Lambert Absorption Law

The transmission of monochromatic electromagnetic radiation through an absorbing gas is modeled by the Beer-Lambert relation:

I(λ) = I₀(λ) · exp[-σ(λ) · N]

Where $σ(λ)$ is the molecular absorption cross-section and $N$ is the column density along the optical line of sight.