Spectroscopy 2050 – The future of ultrafast 2D-IR spectroscopy

The intention of this review is to reflect on the development of ultrafast 2D-IR spectroscopy to date and to attempt to envisage how the technique might develop in the period between now and 2050. As ultrafast 2D-IR spectroscopy measurements were first-reported in 1998, the timing of this article represents a 'halfway' stage, allowing us to look back on 26 years of development to provide a perspective on what the next 26 years might bring. We begin by briefly introducing the method and summarising the development of 2D-IR experiments thus far, but then focus on the most recent advances in technology, sample handling and data analysis methods to inform a discussion on the direction of travel for the field in terms of measurement capabilities. Finally, we examine the most recent applications of 2D-IR, with a particular focus on emerging research areas to show how the field continues to explore new challenges and provide novel insights.