NOVELTY - The system (100) has an electromagnetic radiation source (114) for generating mode-matched electromagnetic radiation (116) that irradiates gas-mixture (102) filled in a gas compartment (106) at determined pressure bars. An intensity enhancement mechanism (124) internally reflects mode-matched electromagnetic radiation at times to achieve effective intensity of reflected electromagnetic radiation (140) in a region-of-interest (130). A detection subsystem analyzes the gas-mixture based upon Raman scattered photons emitted from the region-of-interest.    USE - System for analyzing gas-mixture e.g. natural gas sample collected from gas pipeline or oil pipeline, liquid nitrogen gas, synthetic gas, liquid petroleum gas, process gas, sour gas and sweet gas (all claimed), for determination of composition of gas-mixture, determination of concentration of gases in gas mixture, determination of energy content of gas-mixture and determination of British thermal units (BTU) of gas-mixture, for commercial and industrial applications. Uses include but are not limited to heating applications, cooking applications, power generation applications and transportation applications.    ADVANTAGE - The system enhances signal-to-noise ratio of Raman signals by using the intensity enhancement mechanism that achieves desired effective intensity of electromagnetic radiation at the region-of-interest and by controlling pressure of the gas-mixture to enable precise determination of presence and concentration of gases in the gas-mixture in real-time in a quick manner. The system avoids a need to require expensive and bulky electromagnetic radiation sources to analyze the gas-mixture such that the system is compact in size and field deployable.    DETAILED DESCRIPTION - The radiation source is a coherent source, an incoherent source, a visible light source or an infrared source. The region-of-interest is a concentric point, a confocal region, or a collection of confocal points of the intensity enhancement mechanism. An INDEPENDENT CLAIM is also included for a method for analyzing gas-mixture.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of a system for analyzing gas-mixture.    System for analyzing gas-mixture (100)    Gas-mixture (102)    Gas compartment (106)    Electromagnetic radiation source (114)    Mode-matched electromagnetic radiation (116)    Intensity enhancement mechanism (124)    Region-of-interest (130)    Reflected electromagnetic radiation (140)