1：Experimental Design and Method Selection:

A molecular beam apparatus was used to generate Ir+ by laser ablation and expose it to controlled amounts of CH4. IRMPD spectroscopy was employed with IR light from a free electron laser over 500–1800 cm?1, and photodissociation was monitored using a time-of-flight mass spectrometer. Theoretical calculations (B3LYP/def2-TZVPPD geometry optimizations) were used to compare computed IR spectra with experimental data.

2：IRMPD spectroscopy was employed with IR light from a free electron laser over 500–1800 cm?1, and photodissociation was monitored using a time-of-flight mass spectrometer. Theoretical calculations (B3LYP/def2-TZVPPD geometry optimizations) were used to compare computed IR spectra with experimental data. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Iridium sample ablated to produce Ir+ ions, methane/helium mixture (～1:5) introduced as reactant gas. Data from mass spectra without and with IR exposure.

3：List of Experimental Equipment and Materials:

Molecular beam apparatus, Nd:YAG laser (second harmonic), free electron laser (FELIX beamline), time-of-flight mass spectrometer (orthogonal reflectron type, mass resolution ～1700), microchannel plate detector, helium gas, methane gas.

4：Experimental Procedures and Operational Workflow:

Ir+ generated by laser ablation, cooled and transported by helium pulse, reacted with CH4/helium mixture, molecular beam collimated and irradiated with IR pulses, ions extracted into mass spectrometer and detected.

5：Data Analysis Methods:

Depletion and growth yields calculated from mass channel intensities, corrected for laser power fluctuations. Theoretical spectra compared to experimental IRMPD spectra using Gaussian09 software with B3LYP/def2-TZVPPD level of theory.