Test #3- Spectroscopy & Quantum Mechanics

What is spectroscopy?

The study of the interaction between electromagnetic radiation and matter.

How are color and energy related?

Color corresponds to specific energy levels; higher energy is associated with shorter wavelengths (e.g., violet), and lower energy with longer wavelengths (e.g., red).

What is the relationship between energy and frequency?

Energy is directly proportional to frequency: E=hνE = h\nuE=hν, where hhh is Planck’s constant.

What is the relationship between energy and wavelength?

Energy is inversely proportional to wavelength: E=hcλE = \frac{hc}{\lambda}E=λhc​, where ccc is the speed of light and λ\lambdaλ is wavelength.

What are the regions of the electromagnetic spectrum in increasing energy?

Radio < Microwave < Infrared < Visible < Ultraviolet < X-ray < Gamma

Rank the energy levels in a molecule.

Electronic > Vibrational > Rotational > Translational

What is the function of a spectrometer?

measures how matter interacts with light by analyzing absorption or emission spectra.

What are the key components of a spectrometer?

• Light source

• Wavelength selector (monochromator)

• Sample holder

• Light detector (readout signal)

What are absorption lines

occur when electrons absorb photons and jump to higher energy levels.

Emission lines

occur when electrons release energy and drop to lower levels.

What does the Beer-Lambert Law state?

Absorbance is proportional to the concentration of the absorbing species.

What are the six tenets of quantum mechanics?

• Particles behave as both waves and particles.

• Measurement affects the system (wavefunction collapse).

• Energy levels are quantized.

• There is inherent uncertainty in measurements (Heisenberg's Uncertainty Principle).

• Quantum superposition allows multiple states at once.

• Quantum entanglement enables correlated states over a distance.

What is Schrödinger’s Cat thought experiment?

A quantum system (the cat) remains in a superposition of alive and dead until observed, illustrating wavefunction collapse.

Copenhagen Interpretation

Measurement collapses the wavefunction into a single outcome.

Many-Worlds Interpretation

• All possible outcomes occur in parallel universes.

What does the EPR paradox suggest?

Quantum entanglement allows information to appear to travel faster than light, challenging classical physics.

What did John Bell and Alain Aspect contribute to quantum mechanics?

They proved hidden variable theories were incorrect and confirmed quantum entanglement through experiments.

What is quantum cryptography?

A security method using quantum entanglement to encrypt data, making it theoretically unbreakable.

What are the typical timescales of chemical reactions?

• 10−1510^{-15}10−15 s: Electronic transitions

• 10−1210^{-12}10−12 s: Vibrational & rotational transitions

• 10−910^{-9}10−9 s: Fluorescence emission

• 10−610^{-6}10−6 s: Phosphorescence emission

• 10−310^{-3}10−3 s: Nuclear relaxation

• Seconds to minutes: Biological reactions