1. What is Wavenumber?

Wavenumber (k) is the reciprocal of wavelength, representing the number of wave cycles per unit distance. It is commonly used in spectroscopy and has units of cm⁻¹ (inverse centimeters).

2. How Does the Calculator Work?

The calculator uses the fundamental relationship:

Where:

• \( k \) — Wavenumber (cm⁻¹)
• \( \lambda \) — Wavelength (cm)

Explanation: The wavenumber is simply the inverse of the wavelength when both are expressed in consistent units.

3. Importance of Wavenumber

Details: Wavenumber is particularly useful in infrared spectroscopy as it is directly proportional to the energy of the radiation. It provides a linear scale for vibrational energy levels.

4. Using the Calculator

Tips: Enter the wavelength in centimeters. For nanometers (nm), first convert to cm by dividing by 10,000,000 (10⁷). The value must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between wavenumber and wavelength?
A: Wavelength is the distance between wave peaks, while wavenumber is the number of waves per unit distance.

Q2: Why use wavenumber instead of wavelength in spectroscopy?
A: Wavenumber is directly proportional to energy, making spectral features appear at linear intervals.

Q3: How do I convert nanometers to wavenumber?
A: First convert nm to cm (1 nm = 10⁻⁷ cm), then take the reciprocal.

Q4: What are typical wavenumber values in IR spectroscopy?
A: Mid-IR ranges from 400-4000 cm⁻¹, near-IR from 4000-12500 cm⁻¹.

Q5: Can wavenumber be negative?
A: No, since wavelength is always positive, wavenumber is always positive.