GT Science Tutorial Notes: Rotational, Vibrational, and Electronic Spectra

Introduction to Spectroscopy

• Spectroscopy: Branch of science dealing with spectra formed by the interaction of electromagnetic radiation with matter.
• Importance: Helps understand different properties of matter.

Types of Energy Levels in Molecules

• Molecules have different sets of energy levels with varying energy gaps:
  • Rotational Energy Levels:
    • Energy gap is very small.
    • Transitions occur within the same vibrational energy level.
  • Vibrational Energy Levels:
    • Energy gap is moderate (between rotational and electronic).
  • Electronic Energy Levels:
    • Energy gap is very large.

Rotational Spectra

• Also known as Microwave Spectra.
• Occurs when:
  • Molecule absorbs low energy causing transitions between rotational energy levels within the same vibrational level.
• Example: Transition from one rotational energy level to another in the same vibrational energy level.
• Graphically: Represents transitions within rotational energy levels.

Vibrational Spectra

• Also known as Vibrational Rotational Spectra.
• Occurs when:
  • Molecule absorbs sufficient energy to transition between vibrational energy levels within the same electronic level.
• Characteristics:
  • Transitions occur from one vibrational energy level to another.
  • Wavelength in the infrared region (thus called Infrared Spectra).
• The transition involves both vibrational and rotational energy levels.

Electronic Spectra

• Also known as Electronic Band Spectra.
• Occurs when:
  • Molecule absorbs high energy causing transitions from one electronic energy level to another.
• Characteristics:
  • Along with electronic spectra, vibrational and rotational spectra are also formed.
  • Transitions occur across electronic energy levels.

Summary

• Three main types of spectra discussed:
  • Rotational Spectra: Low energy transitions within rotational levels.
  • Vibrational Spectra: Moderate energy transitions across vibrational levels.
  • Electronic Spectra: High energy transitions across electronic levels.

Conclusion

• Understanding these spectra helps in analyzing molecular behavior and properties.
• Encouragement to share the video for wider learning.