The infrared spectra of the carbomonoxy derivatives of the hemoglobin components I and IV from trout have been measured in the CO stretching frequency region using a high resolution infrared spectrometer. The CO stretching frequency of Hb I CO is very close to that of carbomonoxy human hemoglobin and is pH-independent. In contrast, the CO stretching frequency of Hb IV CO is higher and shows a small but significant pH dependence in the range 6.2-7.8. These results point to a decreased strength of the iron-CO bond in Hb IV CO at low pH, in agreement with the conclusions drawn from the reported difference spectra of Hb IV CO as a function of pH.

The Compact Linear Collider (CLIC) is a mature option for the future of high energy physics. It combines the benefits of the clean environment of $e^+e^-$ colliders with operation at high centre-of-mass energies, allowing to probe scales beyond the reach of the Large Hadron Collider (LHC) for many scenarios of new physics. This places the CLIC project at a privileged spot in between the precision and energy frontiers, with capabilities that will significantly extend knowledge on both fronts at the end of the LHC era. In this report we review and revisit the potential of CLIC to search, directly and indirectly, for physics beyond the Standard Model.