I have recently been reading Christopher Bonanos' biography of the famous New York photographer Weegee. Weegee's reputation grew in the 1930s as a news photographer covering mostly crime and fires at night. He soon developed a style that transcended standard news pics partly due to his innate sense of a good image, but also his shots of the reaction to events, as much as the events themselves.
One item in Weegee's armoury, besides his police radio and pocketfuls of flashbulbs, was infrared. He picked up on it in the early 1940s, a few years after it become available from companies like Kodak through regular retail channels. Before the mid 1930s, if you wanted to take infrared photographs you had to sensitise the plates (for it was plates) yourself. Now there were plates with a sensitivity beyond 700nm which could survive being retailed and being carried around by a busy photographer.
Bonanos places Weege's first use of IR for publication in April 1942, shooting during a wartime blackout drill. He returned to the medium "again and again" using the phrase "Made with invisible light" and many of his most recognisable shots were made this way. He shot audiences in cinemas, the opera and even a circus. Sometimes by rigging IR flood lights or more often by using flash with special IR-pass coated flash bulbs.
My favourite, entitled Opening Night at the Met was taken on December 3rd 1944 and shows a small group in the audience, including a priest and a lady with opera glasses. Behind them stand two women and a man. He is displaying classic IR 'five o'clock shadow' (caused by IR penetrating the skin slightly ... he was probably clean shaven) and one woman shows another feature of the infrared look, which makes eyes look like dark pools. This may well be Kodak film but it shows little of the usual IR film look with halation. This is simply because it would have been a half-plate negative: the effects are there but more subtle than we got with 35mm film.
I can't directly show you the image but I can link you to it on the Getty site. It's a gem: Opening Night at the Met. They're watching Faust by the way.
Getty have 84 more examples of Weegee's infrared photography. This search will get you there. Alternatively, there are 43 shots online at the International Centre for Photography, where Weegee's archive is held. These include some of him with his infrared kit, ready to shoot, and even disguised as an ice cream seller.
Via the Bonanos book I discovered that not only was Stanley Kubrick an admirer of Weegee (his "last great set of photographs" was shot during the filming of Dr Strangelove) but Kubrick used infrared several time during his earlier career as a photographer. Some examples of his work for Look magazine can be found online, although it's unclear how many were actually published. One striking shot, very reminiscent of Weegee's work, is from a set Kubrick shot for Look in a set titled "Park Benches-Love is Everywhere," from 1946. In it, a young couple are seen disturbed in mid-kiss on a fire escape, looking up at the camera. It has the classic characteristics of an infrared portrait, with dark-pool eyes, and the light pattern tells us it was shot with flash.
You can find the fire-escape photo, along with other Kubrick stills work, in this review of a retrospective exhibition in 2018 called Through a Different Lens: Stanley Kubrick’s Photographs.
There's some interesting information on infrared flash in a blog post by social documentary photographer Daniel D. Teoli Jr, including the kind of bulbs used by Weegee. In case you're wondering, electronic flash guns do give off infrared, so you can filter them for candid photography. Usually, no-one will see the flash unless they are looking at the gun, in which case they'd maybe see a brief dull red light. This would be partly due to the very low sensitivity of our eyes to very deep red going on infrared (0.01% of our green sensitivity at 750 nm according to Allen's astrophysical quantities) and to the tiny amount of deep red that the filter lets through.
Christopher Bonanos' biography of Weegee is called Flash: the Making of Weegee the Famous and is published by Henry Holt. It's a very readable account not only of the man's eccentric life but also, in passing, builds a picture of what it was like as a jobbing news photographer on a crime beat in New York between the 1930s and 1940s in New York. And I am cited twice in the notes.