From Ghosts to Atoms: The Story of Spectroscopy

Synopsis

In this presentation,  we explore the story of how spectroscopy evolved from an optical mystery into the foundation of quantum physics. It begins with Isaac Newton in 1672, who split light with a prism and named the "ghostly" colors a Spectrum but could not explain the physical origin of its colors. By 1860, Bunsen and Kirchhoff established the field by proving that these spectral lines were actually unique elemental signatures, a breakthrough that led to the discovery of novel elements like cesium and rubidium. We examine how this tool revealed helium on the Sun, 27 years before its discovery on earth. We explore how the challenge of decoding the hydrogen spectrum led to Niels Bohr’s 1913 breakthrough. His work effectively began to explain these spectral lines of hydrogen by introducing the concept of quantization of electron orbitals. Finally, we show how this logic of quantized energy jumps was applied beyond the electron to molecules and nuclei, creating the physical basis for modern tools like Infrared (IR) spectroscopy and Nuclear Magnetic Resonance (NMR).